Hiya,
I was toying around with using .album (or .alb for people using older systems), instead of the usual _album suffix and .mp3 extension (_Album has pretty much become the universal suffix now, departing from using individual album making software initials), and it works perfectly. All I had to do was click it and quickly tell it which media player it was to be associated with. Album art and tags are untouched, and work just fine.
However, while testing things out, I discovered that MiO's album maker can't tell it's an album being loaded (for unpacking). A quick change of the extension back to mp3 and all's well again.
So, I figured I'd pop in and ask if ".album" and ".alb" could be added to the recognized extensions, so that the album maker would understand they're albums being opened. Not a big thing, but it would be very handy.