Tweets are an asset
I see a lot of interest in taking a group of users' tweets and repurposing them as content on another site. For instance, consider a news agency with reporters maintaining active Twitter accounts. This hypothetical agency often wants to display their tweets on the company website.
One thing about corporate entities is they like to pay for services like these because cost communicates longevity, value, and quality. Creating a service that will group tweets, strip out irrelevant content (e.g. @replies), and allow efficient syndication is something worth paying for. You're only limited by the amount of value you can add to the stream and the chosen method of redisplay.
Are you working on this? What niche are you targeting?
Well we like to think we can do a lot more that just repurpose content on the site. There is so much more interesting data that can be used.