TwapperKeeper is a young site trying to help you organize your own tweets using hashtags. It is a bright and very bland UI but the idea has promise as people pour more data into Twitter.
They are now whitelisted which allows them to poll ever 5 minutes and build an archive on your Twapper tags. You then get not only an archive but folders for such things as news and presentations as it looks at keywords in tweets.
You can see a sample twapper right here. They aren’t letting you delete one you create yet, so be careful there.