I don't mind junk mail, but what irritates me are ones with no return address (or an address that makes it look like an official government agency when it is really a private company). Also ones with the phrases 'to be opened by addressee only' and 'personal and confidential' on them.

One way to get some satisfaction is to take all of your junk mail from that day (just remove your name and address from it) and stuff their postpaid return envelope with it. Helps you get rid of your junk and it costs the company to get the junk to them.....