At a rough count I have 32 third party applications installed on my Mac (not including stuff that came with my accessories like camera, GPS and printer). Two of those are paid-for applications, a few are donation-ware. Just one is now supported by the new Mac App Store, TextWrangler, but it doesn’t say so on the product web site.
The only benefit that I have seen from the store is that I may buy Pages now that is is available as a separate download (but curiously it doesn’t say that on the product web site either!)
SuperDuper, Springy, Crossover, CyberDuck, Sbooth Max, Firefox, SourceSource, SoundFlower, SoundApp Reborn, LineIn, LAME, Growl, KeePassX, Perian, Flip4Mac, XNJB, TextWrangler, NeoOffice, Gimp, PaintBrush, Adium, PopFile, Skype, Sonos, Thunderbird, uTorrent, VMware Fusion, Adobe Air, BBC iPlayer, Adobe Flash, Audacity, SilverLight