I've blocked certain feeds for fan pages and whatnot because while I support them, I don't want to read every single post from them. I have yet to block any particular person though I've been both blocked and deleted. It's hurtful when you figure that out, especially if you thought that person was a friend, but c'est la vie. You can't please everyone.
When I get friend requests I don't want to accept, I just leave them up rather than hitting ignore because there's a contingent of old high school folks I know who just keep re-requesting you add them. This way they can't keep doing that. It just keeps on pending.