Just a heads up about GM's Day - I did not have a chance to look around the first few days, but there is some good stuff out there, just looking at the items going for $1 and my own experiences:
E.N. Publishing - all E.N Publishing material is $1
Elements of Magic: Mythic Earth - my choice for a Spycraft magic system. (I still need to rewrite my Spycrafted version of the Mage class from the book -it seems to have gone west while I was transferring files to my new computer.....)
Adamant - ditto
Thrilling Tales Omnibus Edition - 1930 style pulp gaming. This has some really good stuff for Spycrafting.
Victorian Age - Victorian style pulp gaming (not available in a single large volume though).
Scenarios for these games might well be modified to Spycraft to good effect.
Mars? I have no idea, but looks pulpy.
Anyone else have things to add to the list?
The Auld Grump