It depends on how you want to work, user based or just in general.

You can get all tweets from a specific person (this would be handy for a website where you sign up for) with a certain keyword, or just get them all and scan server side.

On the other hand, you can for example scan for popular developers hashtags (like #ruby, #php, #linux, etc) or just request recent tweets and scan for what you need. These 2 solutions would be perfect for a general scan.

I'm currently working with the twitter api for a small personal project and it's pretty flexible, you have quite a lot of possibilities...