Oh God....where do I begin?
Davidoff Special 53
Davidoff Diademas Finas
Davidoff 100th Anniversary Robusto
Avo LE 05
Avo LE 07
I think those are the saddest discontinuations for me (well, not so much "discontinuations" as they were a one-time, limited-release cigar, never to be made again
).
You can still find some of the 100th Anniversary Robustos here and there but they are dwindling fast. So, if you want any more, start working your way through the Yellow Pages...