"On the Job" is a beautifully simple time tracking and invoicing program for Mac. Unfortunately, I don't have any business. So if you want some PowerPoints made, call me up so I can use this damn software.
I know none of you use Macs, so the rest are web-based:
Netvibes for custom start pages... Much better RSS integration than Google homepage and it's just prettier overall.
Wordpress.com for free hosted blogging. I like the interface more than Blogger, plus the search engine results are RIDICULOUS.
Slideshare.net is kind of a YouTube for PowerPoints and other slideshows. I'm not sure if I'd say it's "really good," but it's the best of its kind.