Some of our table maps came from past issues of National Geographic; others we found online, printed in sections, and taped together. BTW, in addition to being possibly the classiest magazine in the world, National Geographic has an amazing website, a vast and fabulous resource for teachers. You will find more there than you could ever believe for every grade and every subject, NOT just geography.
But this post is about maps, so here it is: NatGeo Map Maker allows you to download, print, and assemble huge maps for your classroom - the World (both political and physical), the Americas, Europe, Asia, Africa, Australia and Oceania, the United States, and Polar Regions. A tutorial provides helpful hints on laminating, etc. Isn't this pic from the NatGeo site awesome?