I was digging the idea of a Web 2.0 Roll-up and remembered that I’ve been gathering lists of Web 2.0 apps and companies (wait, are they the same thing in this case?) that make it clear that a variety of roll-ups are possible.  They also clarify that the whole phenomenon is beyond any individual’s grasp, though alarm:clock’s comment that "features are being launched as if they are companies" does remind us of why there are so darn many of these special entities.

I think I started gathering Web 2.0 lists when I encountered Nick Denton’s Startup kit that leaves out coffee but includes various Web 2.0 features/apps/companies.

Selected Web 2.0 Lists:
Companies and Products on TechCrunch
TechCrunch: A Taste of DEMO 2006
Web 2.0 Innovation Map

A List of Web 2.0 Blogs:
Web 2.0 Workgroup

Please do add related lists in the comments and I’ll come back for an update.