I scored a great 8x10 Ballard seagrass rug for $90 (including shipping!) thanks to this post from Copy Cat Chic. So that will probably be going in the DR since I love seagrass and I think it holds up really well in dining rooms.
BUT before I bought the seagrass, I had stumbled across this post from a google search on "painting rugs."
The blog author used a very cheap (like $12) 9x6 outdoor rug, taped off a simple design and rolled on some paint.
I think the blue she chose is cute for the outdoors, but for a dining room, I would stick with black or white on the taupey gray rug base.
I think the possibilities here are pretty awesome: stripes! zigzags! Greek key! Trellis! Let your imagination run wild. Maybe try an over sized stencil from Whitewall & Co.?
And just in case it's bugging you a little (like me) that the edges aren't finished, you'll be happy to know that most flooring stores will bind carpet for less than $2 per linear foot. For a little more, you can get thick twill tape, like they use on natural fiber rugs.
I'm sad that I don't need to use this idea. Someone in need of a cheap, stylish and kid-proof dining room rug, please get creative and show me what you can come up with!!