Radio Promos were more important to the show in the begining because the show was cross promoted. These days, not so much, but, Luna still enjoys making the promos, and they are used as 'bookends' to the breaks taken mid-show. As you can see, there's a long list. Sometimes they get retired, and replaced. Some of them are getting pretty old right now, and will be started to get replaced soon.
Here Are The Currently Running Radio Promos: