Grading Coins

Theres a lot of info on these two sites just browse around for what youd like. Right now PCGS and NGC are considered the two best, ANACS is good too then ICG.

http://www.pcgs.com/

http://www.ngccoin.com/

Also stay away from coins graded by SGS they are HIGHLY over graded and not reputable

if you are wanting to send a few coins in to be graded for protection or authentication purposes and are not planning on selling them anytime in the near future then ANACS is probably the best one to send them to because you do not have to join any club to have submission privileges. PCGS and NGC brings more money when sold (in that order) but if that isn't in your plans then ANACS is just fine to submit them to. ANACS will bring more money when sold than any of the others not mentioned though. I know some people that send them into ANACS when they are trying to test their grading skills so they have an expert opinion on what the coin grades so they can see how close their grading is against the expert graders and ANACS is alright for that as well in my opinion.

You should consider getting your self a copy of the ANA Grading Standards for U.S Coins which covers mostly circulated grades. How to Grade U.S Coins helps to explain the processes in grading unciruclated grades. You can also check out the PCGS Photograde.