.NET Expression Tree / Lambda Lifting framework?

Anybody know of a nice package that allows implicit editing of Expression Trees? Since you can't really edit them, jus开发者_StackOverflowt returning a new tree would be fine. Easy methods for Lambda lifting (or 'funcletization') would be a nice bonus.

I remember a while back I was looking into this and I thought I found something but I can't remember the name...

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LINQ IQueryable Toolkit and the series of blog posts from whence it came.