Jump Rings for Chain-Making
I found a nice source for jump rings: Spiderchain Jewelry. Some very helpful pages are the Favorite Weaves and Sample Pictures. The "shopping cart" is really a calculator that sends an email with an order number to you and to Spider. You then follow up separately with payment (PayPal accepted). You can include some comments about what you're trying to build (which I did) and Spider will sanity check your order (which he did) which is a nice touch.
My magpie eye got stuck on the niobium rings, which are especially pretty in mixed colors. I got these: air mix. Now I just hope they get here in time for the Bead Party this Saturday :-)