There is the baby lens and its different kind of gls as well as a pinhole variation and there is the possibility to drill a hole in your protecting cap for your DSLR. Now you can have it made for 50 bucks if you aren't able to do it on your own.
Is it worth the effort? Does it get more dust on your sensor? I don't know, but on the other hand it seems to be a lot of fun, because you immediately can see your results.