I'm a lurker. I lurk on several other blogs. I go in and read their posts and then panic and can't think of a good comment so I don't leave one (kinda like with answering machines).
What's worse is sometimes I read something that gives me an idea. Not stealing their idea you understand just, "that reminds me of this one time at band camp". Sometimes I will point that out but I don't want to keep saying, "something so & so said made me think of this" because then I feel like I'm beating people over the head with the other blogger but then I feel guilty that they didn't get the credit. It's like I'm having a conversation with someone but they aren't aware I'm talking to them.