I just finished implementing a really bare-bones smartphone-compatible web-based RSS aggregator.
Best feature: No typing in of feed Urls; just give it a single Url to an OPML file and you're good to go. Of course, typing in that sort of address is still really painful, so I will have to see how I can address that problem.
Total time to implement: about 90 minutes.Amount of that time spent relearning everything I've forgotten about ASP.Net: about 75 minutes.
wow, I know I sound like I'm just drinking the kool-aid here, but I love ASP.Net. It is unbelievably easy-to-use, and so easy to work with.
(a caveat: I most definitely did not write the RSS parsing framework that I am using here. It was something partially written by my friend, Rob Wlodarczyk).
I would post a few digital cam pix of this thing in action on my MPX200, but I am really lazy, and this thing is still really ugly. This round of work on it was more of a proof-of-concept than anything else. I'll put something a little more substantive up in a day or two.