I can totally agree with the contests and giveaways concept. I am currently running a promotion where 5 lucky people get an invite to Google Wave. That is working wonders for me at the moment when I promote it on social networks, including Twitter. Just be aware that, I mean, from my experiences, when you promote via twitter, alot of bots do visit your site, Whilst these may count as page views, they dont count as paid impressions. At least 50% of my visitors are bots when I promote via Twitter, and my fill rate decreases significantly as well due to this. This may not be the case for everyone, for me it happens alot though.
and it really was the annoying part of twitter, like I care about moonfruit and its price. For me it was just another form of twitter spam.
+1 for contests. Your going to have to work an angle and get some spanking prizes to get real buzz with few initial followers. I can't really seem to get my followers to buy into our twitter, I can get them to follow us, but not interact...