Shoulder stretches and exercises?

I've had persistent shoulder problems. It's not a rotator cuff injury, but the muscles in the rotator cuff are perhaps weak (supra spinatus, infra spinatus).

I went to an orthopedist and a physical therapist. It got me back to 80%, but I want to be pain-free before I go back to squash.

What stretches and exercises do people do?

Any other strategies to protect your shoulders?

Dan
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Oh .. and any good resources

Oh .. and any good resources (web sites, books DVDs) for said exercises and stretches?