I'm guessing the training is the main thing that holds most alts back from getting seriously developed, people don't want to devote weeks away from training their main to increase the utility of their alts. At least that's what dominated my strategies and skill selections - I'd plan things ahead of time in Evemon to tune the learning plan, and try to take advantage of those times when my main was spending time in a PVP clone without implants.
Two of my alts were created under the old character creation system, they started out with roughly 800,000 sp, I didn't really train them until Apocrypha changed the rules and added the 100% training time boost, this speed boost is a huge help to creating alts focussed for their tasks and while it was nice to be able to create a Gallente pilot with Drones 5 out of the box, it was rather less useful to have Drone Navigation 5. (For those of you who joined Eve after apocrypha you can get an idea of the old character creation system from online tools like this one). Nowadays you only get about 50ksp, so you end up with 750k more skillpoints trained at double speed in the skills you choose - for most things you want alts to do this is generally going to work out better for you in the long run.
So what do you do with those alts? Well - here's a few pointers
Planetary Interaction - The new stuff, it has the advantage that once you're setup you just need to login maybe every day or so to restart extractors and pickup finished products. Training time is light, new characters come with the pre-reqs for the basic skills, and all you need is a big enough ship to deploy the command centers, It's quite possible to carry and deploy them via cargo expanded astrometrics frigates.
Market Trading - They can sit in the market hub of your choice and update orders, trading skills let you place more orders and extend your reach, but you can make cash without any real skilltime invested. Only danger is that you realise your 'alt' is making more money than your main and turn into a full time trader.
Datacore Farmer - Requires a chunk of training time to get the skills (Science 5, Engineering/Mechanic/Electronics 5, Research 5, Lab Operation 5), and a bunch of missioning to get the standing, but once you do the datacores just keep getting produced and the only thing you need to do is pay your R&D agents a visit once a month.
Research Alt - There's always such long queues at the research slots in hi-sec, but you can compensate for this somewhat by queueing up lots of work across alts. Very easy to get skills for ME/PE/Copying and if you've got a datacore farmer setup then this is included for free. Invention takes more work, with you needing 2 science skills and a racial encryption methods skill too.
Manufacturing Alt - Get production efficiency to 5 and you can grind out more stuff, and we all know more stuff = more profit.
Neutral Hauler - Need to move something in hi-sec when your corp is war-decced - train up an alt and have them move it for you, it'll take less than 12 hours to get in a hauler. I recommend an Amarrian toon for this since the Sigil only needs Amarr Industrial 1, plus for smaller stuff you can move decent amounts in a Magnate (as demonstrated by the number of obvious macros running courier missions in a magnate.
Neutral Scout - No training needed at all, just fly the noob ship to the scout system and profit. It's nice if you can get a cloaking device, or even just make a frigate unprobeable with ECCM, it's even better if you train for covert ops.
Cyno Alt - All you need to train is Electronics 5 to get access to Cynosural Field Theory then you can put up that big sign that says "I'm Here, Gank Me!" so that your friends can jump in their expensive cap ships and then dock up while you sit stuck in space until you're destroyed. The nice thing about having your alts trained for this is it's quite often that your friends will be hunting around for someone in the right place to light a cyno, so having multiple extra options will make you lots of friends.
No Strings PVP Alt - Join Red Vs Blue and have some fun, or just
So, anyway, I tend to combine most of these functions into one - Datacore Farming, PI, Hauler, Trader, Cyno Alt - and so I spent some time trying to come up with an optimal skill plan that would minimize my training time.
I mused about the best starting race for some time -
Amarr - Win lots of points for hauling and PI because the Magnate and Sigil have lots of low slots which can make them really capacious, or harder to catch with the aid of a full rack of WCS's. They're excellent for managing PI in low-sec. Shame that they don't really have any effective low SP combat ships for missioning or PVP.
Caldari - They're the best race for missioning, The AML Caracal will make standing grinding a whole lot easier, and you'll need to do lots of grinding. They also have specialist ECM ships which are a gift to Low SP PVP, except that RvB bans ECM.
Minmatar - The Rifter and Thrasher are nice for mission grinding, but with low skillpoints I can't find a cruiser which is suitable. The Mammoth is also an excellent hauler if you want to train Minmatar Industrial up to 4
Gallente - drones are nice, especially for semi-afk mission grinding, but unless you train drones 5 you're missing out on Drone Interfacing which gives a huge boost to drone effectiveness. They also have the best Hauler in the form of the Iteron V, but that requires quite a big of investment, and by the time you're there you're already thinking about making your alt a freighter pilot.
In the end I went for an Amarrian pilot, trained frigate to 3 for the Punisher and Amarr industrial 1. Then I started training Caldari Frigate to 4 so I could Get Caldari Cruiser and fly the caracal for mission grinding. The industrial skills are all rank 4 so going purely Caldari and training Caldari Industrial to 3 to get the Badger MkII is more training time than training an extra frigate skill to level 3. I made the toon Amarrian because I figured that I'd be more likely to use lasers than I would be to use railguns.
To Get a cyno alt I'd need Electronics 5, which along with Science 5 gives me access to the Electronic Engineering and Electromagnetic Physics Skills, not the best datacores, but it saves having to train Engineering or Mechanic to 5. Add in the important PI Skills to Level 3, some basic combat skills for flying the caracal (general rule - if it gives some useful bonus, or unlocks some type of module then train it at least to level 1), some social skills - negotiation will increase my datacore yield, and some trade skills - feed them all into evemon and come up with implants/learning skills that reduce the overall training time and start cooking.
It's a Pain to grind standing when you're basicly confined to courier missions or low level combat missions, but with good agent choice and some help from other alts you can speed this up immensely.
The Caracal Setup I use for level 2's requires almost no training and is stupidly overpowered for anything it encounters -
Highs: 5xAssault Missile Launchers
Medium: 10mn Afterburner
2x Large Shield Extender
2x Shield Resistance Amplifiers (change as per mission needs)
Lows: 2x Ballistic Control System
Drones: 2x Hobgoblin
Rigs: 3x Medium Core Defence Purger
You don't need to train the skills for the rigs either, just contract the ship to your main, fit them and then send it back. Same applies for the Sigil - stick cargo rigs on it and get 16k cargo capacity without actually having to train Jury Rigging or other skills.
Anyway, between 2 accounts I now have 6 characters working on planets, now my task is to optimize the planet side interaction to reduce the amount of time I need to spend managing it - but that's another article.