Tom at MindHacks has some ideas about why e-mail becomes a compulsion:
Checking email is a behaviour that has variable interval reinforcement. Sometimes, but not everytime, the behaviour produces a reward. Everyone loves to get an email from a friend, or some good news, or even an amusing web link. Sometimes checking your email will get you one of these rewards. And because you can never tell which time you check will produce the reward, checking all the time is reinforced, even if most of the time checking your email turns out to have been pointless. You still check because you never know when the reward will come.
Ditto for those RSS feeds. What to do? Find out here.