I think what you're looking for is:
http://twitter.com/statuses/user_timeline/%USERID%.rss
Where %USERID% is the ID of the user in question.
For example, the url to my own timeline is:
http://twitter.com/statuses/user_timeline/16979198.rss
with 16979198 being my user id number.
UPDATE
According to the Twitter API, you can also do the same with the users username as follows:
http://twitter.com/statuses/user_timeline/%USERNAME%.rss
Where %USERNAME% is the username of the person who's feed you'd like to view.
For example:
http://twitter.com/statuses/user_timeline/jamiedixon.rss
You can also replace the .rss
portion of the link with other data types such as .json
.atom
For further information on the Twitter API and Timelines, visit here:
http://apiwiki.twitter.com/Twitter-REST-API-Method%3A-statuses-user_timeline