I just ordered an "S3 Quad Band Quad Cards Analog TV FM QWERTY keyboard Cell Phone"
I fully expect it to be one step above utter rubbish. But it can use four sim cards simultaneously, so I figured, for 40 bucks, why the hell not?
At some point, I'll probably end up getting at least a dual-card phone. I've been able to stave off needing the functionality a little longer, but I fear I may need it eventually. It's a shame that they don't seem to attract proper development in the same way that single-card phones do, but I suppose it makes sense in terms of how the maker/operator market is currently structured.