The number one frantic tweet I see come up as people are going into the week before the wedding is, "bah, dammit, need table number holders!"
You could go my route, and borrow them from your older sister (or the route of oh, 10 of our friends and borrow them from my older sister), and you can also go the sane route and ask the venue if they provide them. Barring these two options, check Ikea first if you are limited in craftyness, and otherwise, turn to this Photojojo tutorial.
I have a bunch of this florist wire left from trying to make my own flowers, so I'll be testing this out soon. What do I need table number holders for, you ask? Well, over the holidays, I was at my sister's house and noticed that on her mantle, she displayed the holiday cards, which we did as well - but instead of propping the flat cards up against the candles and vases and photo frames on the mantle the way we do, my sister was using her table number holders to hold up the flat cards. It was one of those genius solutions that somebody with no decorative sense (like myself) would never think of, but seemed so obvious once I saw it.