When I manually take song requests, I play a 6 second announcement that the following song is a request. I'd love it if the song request widget could be optionally set to do the same thing. This alerts the listeners that song requests are happening, shows listener and DJ involvement to other listeners, and makes them aware of the service.
Even if the widget simply played a track from a specified playlist before playing the requested song, this would do the trick. The DJ can set one playlist to hold "This Next Song is By Request" jingles, so the widget plays one of them prior to playing the requested song.