A few days ago, I participated in a small focus group about a new site/startup that is just getting off the ground. After sitting through the Vision, the pitch, and a couple rounds of "what makes a site sticky?", I could boil down everything I was thinking to two points:

Give me something useful. My time is the most precious thing I have. If you waste it against my will, you're out. I don't care if you're a great site. I don't care that you may be able to meet my needs someday... maybe I'll come back then.

I need something now. if you've managed to catch my attention enough to get me to click through to your site, I need to see what the value is right now. Make your pitch, you get a paragraph or a couple images at best. If you're the best at aggregating my news, great, say it. If you're a great way for keeping in touch with friends... difficult... but tell me why/how.