I have a need for lots of different kinds of cards (business cards for consulting, business cards for companies, personal cards, cards with just my blog address, photo release cards, among other things). I’ve simply done without rather than get them all printed, but recently I bought a Cardmate business card cutter:
http://www.laminatorwarehouse.com/cardmate.html
This thing is great! I can print 10-up cards on cardstock, and cut them myself. They don’t look quite as good as professionally printed cards, but they’re a huge step up from the pre-cut peel-off cards (which are probably half the weight of good cardstock). The advantages of print-on-demand cards are numerous – you can vary them with your audience, print special colored ones for the holidays, etc…
(On a side note, I ordered it on the phone from ABC Office first and told them I needed it by a particular date, a week off. They said no problem, then sent me an email three days later saying it was out of stock and would be backordered. Until the week after I needed it. Nice. Laminator Warehouse was not only cheaper, they had it, were very helpful, and got it to me on time.)