Bob:

There may be some sites that have them listed, but I haven't done any
searching for them. http://radioreference.com has an aircraft forum, so
if you're a member of that, you might want to post the same question.

http://airnav.com lists airport FBO's and many larger FBO's have a
seperate ops frequency in addition to 122.95 for inbound civilian
aircraft. You'd need to scroll down the page of the airport that you
select until you get to the FBO section.

I just monitor all 127 128.85-132.0 freqs because that's the easiest way
for me to do it and I know that I'm not going to miss anything by doing
it that way. If activity pops up sometime on a new frequency, then that
frequency is already in the radio.

Mark Holmes
Marion, IL