Apart from the 2 CD Ultimate Collection and several releases in the 80s, there is still a vast amount of Jan Hammer' Miami Vice music which still remains unreleased to this day. Some of it probably will never because of Universal's reluctance to allow its release. Much the same with how Tim Truman has been prevented from having his 1989 Season 5 score music released, Jan Hammer's best work remains hidden in the vaults.
Luckilly though, several fan made cover versions have replicated these tracks almost 100% accuratel using the same equipment Jan used such as the infamous Rockman Distortion unit and MXR Flanger. You can find these amazing cover versions done by Rick Leon and Dadrian Wilson.
Recently, I also came across a youtube channel from Crockett1984 which has featured many of the great unreleased instrumentals from the TV Series.
You can find the channel here: http://www.youtube.com/user/Crockett1984
Here is a selection of some of the rare unreleased score tracks extracted from the DVD's. Browse around Crockett's youtube channel to hear plenty more of Jan Hammer's unreleased Miami Vice score instrumentals.