[shep]

In addition to the man pages I find google and an online vendor catalog to be helpful.
My usual plan of attack is to browse the open box section at New Egg and enter the wireless N adapter model number into google followed by "linux" Almost invariably someone has tried the adapter and if semi-knowlegable will post the chipset. I have even been alerted that the manufacturer had changed the chipset while retaining the same model number.
When purchasing I try to speak to a sales person and tell them that I want a particular version with a particular chipset and get assurances that I can make the return without a restocking fee if it does not have the desired chipset. The other tactic I use is to buy locally and have a sales person open the box to look directly at the chipset.

In general RAlink and the older atheros drivers work well and I usually hunt for one those chipsets.