We usually work with developers to help display their applications/work from our site. We do require that the application be both useful and solid (as in stability). We are sales capable and we do take a cut (a negotiated amount between you and us).
If it's good stuff, then we won't pass it up. We are working with other individuals similarly for some upcoming releases (which I'm not at liberty to discuss, atm)
We work non-exclusively, so you're not chained to selling/adverting through us.
Short version: If it rocks, give us a holler.