I cant really say if any of these are considered very rare nowadays but these are the pride of my collection of software on various machines.

Amstrad CPC 464
Bard's Tale
Gauntlet + The Deeper Dungeons

Atari ST
Midwinter

Amiga
Elvira -Mistress of the Dark (The adventure version)
Elite
Frontier

PS1
Monster Rancher x 3 (1 open, 2 sealed)
Diablo

PS2
Gitaroo Man
Unlimited Saga

PC
Daggerfall
Battlespire
Carmageddon Max Pack (The uncensored version, complete with cheat book, mousemat and key fob)

As I said, nothing spectacular (afaik) but I am pleased with what I have retained, especially from the 8 & 16-bit era.