I launched hTime on Hacker News and made it to the #1 topic of interest and discussion for 2 days in a row! The post resulted in 197 comments, 5000+ users, and 15000+ pageviews.
The lessons I learned:
1- Submit multiple times, and don't give up. This was my 6th attempt.
2- Content is key. In every submission, I tried a new tagline. The one that succeeded was the most realistic one with no big, buzz words.
3- Listen carefully to what users say. It's vital to keep an open mind for the negative commenters and not over-excited for the positive ones.