SO, broccoli rabe. Saute it with some garlic and chili flake in olive oil until tender. Blanch it first if you're that kind of person--but me, I get it going in a pan with the other ingredients, then add a splash of water here or there as I cook it if it needs more time to become tender. Perhaps I'm lazy, but to have a pot of boiling water, then a strainer, and an ice bath, well, this just makes too much clutter in a kitchen. Finish it with salt and pepper and lemon, and you're set. Quick and easy. You could also roast it--the slow, dry heat of the oven will rob it of some color but give it some nice brown roasted bits, which will lessen the bitter taste. An article in the current issue of Saveur (October 2011) praises the act of what many perceive as "overcooking" vegetables, that is, cooking them past the popular point of crunch and vitality into a soft, warm hug. Said article has a recipe for broccoli rabe, in which it is cooked with olive oil and water until tender as all get out, and hey, I can get behind that. After all, there's more than one way to skin a cat.
One note--don't be fooled into thinking broccolini is the same thing as broccoli rabe. It'll often get served and sold as such, but it ain't--it's a hybrid of broccoli and Chinese broccoli, and is much more sweet and far less bitter than broccoli rabe. If you eat it and like it, fine--it's delicious--but don't let it go on masquerading as something it's not. Serve broccoli rabe with rich pastas and braises, and let it be it's bitter self. I'll need a like-minded friend after this baseball season.