i'm still a novice, but i know a little bit--
there's base work (moderate off-season cycling you do to get ready for harder stuff closer to the season);
cross-training (also usually in the off-season, i think: it just means doing something other than cycling, e.g. running, swimming, etc..);
weight-lifting (obvious);
also, i think a lot of people commute by bike as well as do race-specific training.
I dunno, that's all I got. Hope that helps!