Thanks for your responses.
I don't know what the exact specs of the socket are, but an Enercell universal AC/DC adapter "H" plug (available at RadioShack) fits it.
I ended up fixing my socket without replacing it. Here's how:
Opened up the cover, and unscrewed the circuit board.
Lifted the circuit board away from the rest of the device (be extra careful of the cord connecting the eink screen to the circuitboard and of the little plastic deal that connects the outside power switch to the real power switch)
Opened the device a bit, so it could stand on edge.
Soldered the broken-off tip to a slightly ground-down paperclip (go-go tin antimony 95/5!).
Clipped the clip to the approximately correct length.
Inserted the clip into the hole left by the broken center pin - adjusted length as neccessary.
VERY CAREFULLY soldered it into place from the back end. If you try this, be careful not to a) melt anything important or b) accidentally connect the circuit to the "ground".
And . . . voila!
Note regarding power switch: the warning comes from the voice of experience. I busted mine . . . so now I can only my PE on/off by opening the whole case. It should be a fairly easy fix - glue a little rod to connect the outside switch to the inside switch. I just haven't had time to do it yet (plus, I'm a little scared that I might accidentally gum-up the internal switch-slide).
Thanks again for the info re: solder-remover. I'll store it away for future reference.