IconBuffet Free Delivery
The Icon Buffet has a pretty cool program called Free Icon Delivery:
Once a month, IconBuffet will deliver a free collection of stock icons (a Free Delivery) to your IconBuffet account. These special icons are royalty-free for both commercial and personal use.
I bet this program does pretty well from a marketing standpoint, because it gets me to visit their site every month to get my free icons. When I'm there I usually browse around a bit. If I ever need to buy some icons, I'm sure they will be the first place I check.
They also allow you to swap icons with other members, if you wanna swap I have Helsinki Hi-Fi, Oslo Atmosphere, Shanghai Tech Smilies, and Tower Grove Melee. Just post a comment, or contact me.
Update: They now let you swap icons on their site...