Twieee will autotranslate Tweets for you making the ability to read the public stream much easier. This was needed for some time as Twitter expanded across the globe. When I tested the site, there was 10 languages supported and it seemed to work reasonably well.
You are able to log in as yourself, view the public stream and a hidden feature. You are able to search for people by hobby. I presume it is searching the bio area of the Twitter profiles, but it was not documented.
A good site to use when you start making friends across languages.