They sure are... the easiest way for me to get lots of icons is either participating in icontests since I don't tend to remember to post those once voting is over or make non-challenge icons with the thought "there'll be another session soon... I'll wait a bit until then"
... months later I start wondering where all the unposted icons come from :D
They get plenty very quickly if you list all of them :D I think I'm moving on from that kind of contest as well and returning to making icons for fun and not contests... I've certainly tried all kinds of contests by now - from regular icontests to LIMS, rumbles and now 20in20s :)