Review my webapp.
modoc: Unless you're praying for a $$$ acquisition it doesn't NEED to be extremely compelling vs. the other sites out there.  If you just want some good user base, and you want to make a few bucks with ads or premium features, having a great UI (which you have) and adding new features is enough.When I wrote 10MinuteMail.com, it was just to learn Seam.  If I'd bothered Googling around, I would have found a dozen existing sites that did the same thing, and I wouldn't have released it.  However, the market size for the problem is apparently larger than the existing dozen sites, and I do some pretty solid traffic/ad revenue on there.  It's not a million dollar sale kind of thing, but if I wanted to I could be leasing a very nice german sports car on the ad revenue.  It really depends on your metrics for success.The to-do list potential user base is enormous, and having an easy to use, pretty looking site, that has good integrations with other systems (e-mail, rss, ical events, gcal, etc...) could do very well, even amongst many existing competitors.I agree with the comments that you should making signing up as easy as possible.  Especially with a free service, the barrier to entry needs to be as low as possible.