Just my two cents...
In 2001 I DONATED a domain name I had registered a year earlier to a state run agency (which falls under charitable donations in the tax law) and was allowed to deduct the "fair market value based" based upon an estimate made at the time by one of those online domain selling brokers popular back then. However since it was treated as capital property I had to declare the original cost (including the annual maintenance (renewal fees) and all other costs I could come up with :-) as the basis and had to claim the rest as capital gains and thus it worked out as pretty much a wash. I used Turbotax to do the calculations and just treated it as personal property.
In the past my method has been simply to call the IRS help line (listed on their website) and ask the specific questions. Their people have always gone out of their way to be helpful (I'm guessing they get paid by the call and time or something so make sure you have a lot of time available to chat) and they have all the computerized manuals and experience of answering similar questions. Then if I don't like the answer I go seek professional help :-). Beware though, certain reports claim even the IRS gets the answers wrong a large percent of the time and YOU are still responsible for any of their mistakes or later changing of their mind.