What about that stamp you can't identify? You know, the one that looks just like another one except for a few engraving lines sticking out from under George Washington's wig? Well, there is someone who sympathises with your problem and knows all about the confusion that can reign, especially in U.S. classic stamps identification. William Weiss has an ID service to tell you what stamp you are looking at when you don't know.
Just start to collect the Washington-Franklin series of the early part of the 20th century and find you are in stamp ID purgatory. But there are plenty other stamps in the U.S. classics area that can drive you around the bend. Weiss can help.
His service is reasonably priced and can be done with a stamp you own, or one you are interested in purchasing as long as you provide an online scan/picture that is clear. Of course, if you are not in a hurry you can mail him your stamp for ID'ing.
Weiss has been in the philatelic business for years and has seen it all, more or less. Another service he offers is expertizing. A certified expert with decades of experience in the U.S. stamp area, he will examine your better stamps, offer you an opinion on their genuineness and issue a certificate that is accepted by dealers and collectors hobby wide.
As your collecting becomes more advanced and you pick up more expensive and rare stamps you need an expertizer to make sure your investment is a good one and that you're purchasing the real goods.
Visit Weiss's website to see the credentials of a man who has over 50 years of collecting and study of every aspect of U.S. stamps. Or buy his services through eBay: there is a link at his site. I used Weiss's ID service and found it quick and professional. Highly recommended.