How can you filter better what kind stuff you want to follow on twitter? Doing some further research on this, I discovered that there are indeed already a few options. First, there's the Twitter Pack Project, a free wiki where you can find users who are only twittering on specific issues. Some people are also automatically feeding their twitter with Twitter Feed, which can then be used to sharpen a twitter profile towards a certain issue.
A great way to create a thematic twitter feed within a community has been presented by the Nonprofit Technology Network. By using a combination of a new common community Twitter account, Twitter Feed, Terraminds and a unique keyword like "ConferenceXY", they were able to produce a collaborative feed on an event where every post of users which contains the keyword "ConferenceXY" is published.
However, I would still love to have in Twitter the option to define different categories (job, private life, hobby X, interest Y, etc). Then anyone of my contacts could suscribe to just the one of my specific thematic feeds which (s)he is interested in. I played around with Photoshop and created the quick concept study below, which shows how such a categories feature could look like in Twitter. Would be interested to learn what you think about it!