I had one of those boomboxes with an internal mic. It was on the most useful and versatile electronic things I've ever owned.
When my band, Missing Neutrinos came over--they always came over to my place--we would jam and record. My more experienced friends knew that working on a piece, interesting and cool stuff would come up--and be lost unless recorded. Sometimes the knowledge we were being recorded gave a kick to it.
We got so much stuff; I have cassettes still.
It's unfortunate we didn't have a better catalogue system. We did so much good stuff, as well as so much drek, I'm kinda glad the band didn't continue longer--I'd be drowning under Neutrino music.
Later, I used it to play my old Yamaha keyboard through my old 386. I thought it was so strange to plug a boombox--or any speakers, really--into my computer. (My 'new' Compaq, of course, came with speakers.)
Soon, however, the motor for the casettes on the record side died. I was so surprised when I went to radioshack and discovered they didn't come with internal mics anymore--good move for them; bad move for us.
I sure had fun with my old boombox!