In this digital age we have a lot of ways to monitor military aircraft. Within VHF/UHF you can monitor not only voice comms, but Mode-S and VHF ACARS digital transmissions.
If you monitor HF frequencies for over the horizon comms the most common communications you will encounter are USB voice transmissions. But there is another ACARS style digital stream you can monitor on HF freqs and decode -- HFDL. It has been around for a while, but it is getting more attention by aero monitors now that there are more than 2000 aircraft worldwide that can send and receive HF digital messages and to a network of 15 different stations located worldwide.
I have added a new reference page with the current frequencies in use on HFDL monitoring to our sister blog the BTown Monitoring Post at http://monitor-post.blogspot.com/p/hfdl-system-table-48-frequencies.html. I will be updating that page as necessary so check back often or become a follower of the Btown MP.
In addition to the new ref page above, I have moved our International Aeronautical HF Frequency List and Civilian Air Cargo/Airline and Select Military Call Signs over to the Btown MP at http://monitor-post.blogspot.com/.
I will be using that blog to consolidate all of our new upcoming HF ref pages and future updates to existing ref pages.