I found this a while ago, then forgot about it, then someone asked recently and I thought I'd add it here to help others find it (including me after I've forgotten about it again).

The Matrox DualHead2Go will let you connect two external displays to your laptop, although after reading the details more closely it's not quite as great as I thought.

The setup is this:
Mac -> analog (not DVI) -> box -> DVI -> two external displays

More info on their website, but basic details are Mac+Windows compatible, lots of resolution support options, and it costs $229.

They also make a 3-display version for $329... Matrox TripleHead2Go