Things to do in Mannheim?

Hi Everyone,

I'm new to Mannheim, although I did visit here as a tourist before moving here. I'm Australian, and have been around the 'big' tourist sites (the Schloss and the Kunsthalle, Wasserturm etc).

I'm wondering if anyone can recommend any good activities/events/sightseeing opportunities in Mannheim? I'm keen to keep active until I get my work situation organised. With this in mind, I would prefer as many inexpensive activities as possible, and preferably with other people around.

Thanks
Lisa