I've just noticed this thread (I don't normally get as far as the BS thread - this should have been in the music section!).
As Mooh said the original D'Angelico guitars can be worth a lot of money. Here's a link to the D'Angelico site, which has some information about him (and a scrapbook showing famout guitarists throught the years who played D'Angelicos) and where you can probably ask for some information about the guitar you have: D'Angelico guitars.
It also tells you about the Japanese produced new range under the D'Angelico name. (I have one of these - they only come in around £3000 in the UK - a fraction of the current price for the originals)