not sure, if this has been covered, but "multiple accounts" could be an interesting topic or even series.
This allows AH buybacks, AH price driving, fast trades between a main and his bank alts, "solo" power-levelling with 2 PC's or 2 windows, Horde and Alliance chars on the same server, advertising in trade while running instances on the other char...and so on.
And I agreed that it was a pretty good idea for discussion, so let's have at it. In addition to the uses he mentions, of course, there's also multi-boxing properly considered, as spectacularly practiced by Xzin (still one of my favorite posts on this blog) -- playing more than one character at a time for fun and profit. Do any of you own multiple accounts? If so, what do you do with them?