One of the more useful websites is www.bowjackson.com. This site has an interactive calculator for many of the more popular arrows.

Then there is always the charts from each of the arrow manufacturers themselves, on their respective websites.
Some of the arrows are marked according to the weight they are to be shot at, assuming an average of about 29". Example might be Gold Tip 3555, 5575, 7595. One thing about most carbon arrows is that if you are on the very upper end of their spine range it's often better to go to the next stiffer arrow. Carbons work better this way.

Easton/Beman is the only company that puts the spine deflection on their arrows. The bigger the number, the more the deflection, thus a more limber spine; eg. .500, .400, .340, .300 with 300 being stiffest. Frankly they are the only ones that do it right IMO.

Carbon express does it backwards, as do some of the other manufacturers. I guess they like to cloud the issue, making us feel like a bunch of dumb asses.