Twitter is one of the Great and friendly site ,Twitter has an API implementation that is very simple to understand and use. if you want to friends friends timelie of user you can use that from here
Ones you find the RSS of friends , you can get the 3 Keywords
1 . Statuses - what are you working on ?
2. friends_timeline - what do you need ?
3. RSS - in which format you need Rss
API supoorting in xml , json, rss, atom you can choose one of that .
Methods supported: See Twitter API
There are many objects supported, but the above format applies for only a few like Statuses, User, Direct Messages. there rest all other are mostly similar.
right now i am working on complete set of wrappers using this api, so it will be easy ,plz leave a comment if you want any help