Are there any particularly good exercises for sciatica?

Yes: Mckenzie exercises are generally prescribed for sciatica or lumbar radiculopathy. Ideally, a physical therapist will design a customized exercise program for your particular problem.

Core Exercises: Typically core strengthening exercises are the best to help relieve pressure and forces in the spine. I would try and google some or look them up on youtube to see descriptions. If you can do them yourself, wonderful otherwise ask your doctor to get a referral to a good physical therapist for further assistance.