For anyone really interested in letting go/releasing, I can't recommend GP Walsh highly enough. That man knows his shit.
And teaches it in a down to earth, practical way.
He addresses many other personal and spiritual topics as well, and can go to just about any depth on them, it seems to me.
Mind you, there are also some fucking great threads on Natural Freedom on the topic of letting go, and Flow has really contributed some great shit to them.
He is a cool guy. I also recommend a guy called Sen from the site calmdownmind.com.
Besides all his writing being free for reading, he is extremely objective and not culture specific which is important to me.