First off, I think there is a need for this type of thing, and I would use something like this!

Some ideas:

  - what does it look like once you login (screenshots)
  - please have an examples page or something like that
  - can I build a list like rails, ubuntu, nginx and have it email me? (examples page)
  - what does the score do? (again, examples page)
  - depending on the data feed, you might also include - 
      app updates, like -- new version of rails, nginx, or flash, etc