Most of the startups that are making money are the ones you've never heard of. This is a pointless exercise...however, here are some that I believe are making money that you may have heard of (happy to be corrected as I don't know for sure that they're all making money):
Although I have no idea if it's even classed as a 'startup'.
I wonder if some of the reason for the recent backlash against advertising supported models is that some techie types install adblock, and perhaps assume everyone does? In my measurements only 6% had adblock installed, and that's for a very techie early adopter crowd.
The truth is, there are millions of websites out there, making millions from advertising. It's so much more scalable than charging users.
If facebook+digg etc cut back spending, they'd be making millions in profit from advertising. I expect they have bigger plans though.
1. GitHub 2. eBuddy 3. Dogster 4. StyleDiary 5. ThisNext 6. Kaboodle 7. Stateless Systems 8. RedBubble 9. Wufoo 10. NationMaster