While browsing around at the airport before Christmas, I ran across this page by PE0FKO about his program IQRec.exe, which is used to record the quadrature outputs from a Software Defined Radio. It includes an example recording of nearly 30 minutes of the CQWPX contest recorded on 40m at 96khz. In theory, that means that it covers 96khz of spectrum, although in practice, it looks like a bit less, no doubt due to roll off because of antialiasing filters in the sound card. Here’s a picture of a short 20 second or so snippet of the recording:

The tuned frequency is centered in the middle: you can see that there are no signals at the very top or
bottom.

This is a very nice little test file, including literally dozens of signals. I’ll be experimenting with it more.