About the only thing I actually use Google Reader for, is synchronisation between devices. I use both Net News Wire and Feeddler -- neither of which are perfect, but the magazine-style RSS readers (such as Feedly, and the like) don't really suit my usage patterns.

I wonder if the answer (for myself, at least) is a basic web-based reader, which uses dropbox for storing synchronisation data. With about 5MB of localStorage, I could also possibly fix one of my bug bears with the clients I use at the moment - offline download of some content (for those train trips where the connection drops like a yoyo). Using the iPhone's safari browser for the reader itself would fix the other problem I have (specifically with NNW) -- poor download and page rendering performance.

There's my spec ↑... now I just need to find the time to develop it... (before July)