Maybe create an API so I can update this from my phone(via app) or maybe allow SMS updating. Mobile use is crucial for me, heck even allowing emails to create new todos/projects would be nice.
It's pretty hard to get reliable worldwide sms delivery, but -- sms for the USA and Europe we can do, I think.
A lot of times you can get away with a decent smart phone interface and just put a few meta tags in the head tag for the iPhone so that it looks slick for the iPhone too.
Maybe you could make it free for people unless they want the advanced features. The features could be sms/email notifications, more projects than x at a time, or whatever you might deem worth charging for. You will need to tweak the business model but so far the site looks clean and usable. Good job.