How many and what are you doing with them?

[Jwoz]

I'm running 10 accounts right now, all mining in null sec. I have a rorqual running perfect boosts, an orca for hauling and 8 hulks with t1 crystals (training t2 atm).

Planning on adding at least another 2 when odyssey comes out.

[LordsServant]

8 accounts.

2 Main loltastic SP chars, living in wspace.

1 Orca Char.
5 Mackinaw chars for mining in nullsec, on same accounts 5 drake/naga alts, currently training for gila/RRdomi for either wspace or lvl 5s. Previously used them in FW, but minmatar tier just tanked so vOv.

[EaTCarbS]

2 Currently mining while I learn the game. Finished the tutorial and the first round of 10 from the first career agent. Need to finish up the other career agents.

From what I've seen so far, mining isn't really worth it unless you're running a blob of accounts. Combat/PvP is more fun and interesting anyway, and is better suited for lower numbers.