I'm looking for start-ups doing innovative work in productivity.

For example, here are 3 innovative groups working in time management (I use them each daily).
Time management methodology  David Allen's Getting Things Done (GTD)
Time management tool for personal use   Remember the Milk
Time management tool for group use   Liquid Planner

I am developing a service for reviewing and selecting cloud based productivity software, but I'd like to be more involved with a group already providing services to the public.