Here are some good resources for you. I don't use them all religiously but I recognize the usefulness/creativity of all of them.

1. This is a cool little scheduling webapp that's worth checking out.
http://www.rememberthemilk.com/

2. Diddo from number one.
http://www.nozbe.com/

3. I haven't gotten to play around with this one yet, but I can see its potential...and I think I like it.
http://www.empressr.com/

4. I'm working my way through Financial Peace University right now, so this webapp was quite intriguing. It's very easy to use and worth a peeksipoo.
http://www.mint.com/

5. Want to send out mass texts easily and without charges? This is the way to go. It's going to be a lifesaver for me.
http://3jam.com/

6. This is just for your churchy folks out there. But it's a very easy to use webapp, simple, and practical. It helps churches track important information and such.
http://www.churchmetrics.com/

7. I personally won't ever use this...I don't think. But if this fits your style of thinking it would be great. It definitely looks nice and seems fairly simple.
http://bubbl.us/

8. This one is fun. You must play.
http://www.mrpicassohead.com/

9. This webapp gives you piece of mind if you're a hardcore blogger.
http://www.bloggled.com/

10. I've got an account for this. I like it. It intruigs me. But I don't use it at all. We'll see where I end up with this one.
http://friendfeed.com/

11. Up until last week when facebook stopped updating my status via my phone this little guy was great. It updates your twitter feed through facebook.
http://twitterfeed.com/

12. Best news site ever. Period. I don't care if it's fair, balanced, or accurate. It's down right fun and that is no lie.
http://doodlebuzz.com/

Oh there are so many more I'd like to share. As I've learned from my friend Jonathan webapps are where it's at...especially a free one.