Here's a few from my collection, limited shades that I wish Mac would re-promote. Sorry if that's more irritating than anything, since it's not like you can rush out and buy them, but maybe people can suggest some dupes? I've found these particular ones really difficult to match.
Lollipop Loving- peach with green-gold shimmer. Peach shades almost never work on me, but this one is a really nice nude
Bubblegum: cool lavender pick with gold shimmer (This one and LL are both glazes, which I feel is a really underrated formula from Mac. They can be sheer, but they do definitely have a personality.)
Strawbaby: soft coral red with blue shimmer. I get compliments on this whenever I wear it. I can't believe this one has never been brought back.
Blooming lovely: Greyed lavender. It's a much cooler shade than Lavender Whip (plus it's an Amplified Creme, so it's more opaque), considerably lighter than Up The Amp
Isis: I cannot capture the full beauty of this one. It's a cool taupe base with very fine silver and green shimmer. Unbelievably gorgeous. It was a permanent shade for Mac up until about 2002. Haven't seen anything like it before or since. Incredibly creamy frost, too.
So Original: Deep purple-berry with silver and light gold sparkle. The sparkle on this one is a little grittier than some (although I don't find it irritating) and somehow makes the lips look fuller and smoother, more so than almost any lipstick I've ever tried. I don't know how that works, but I assume that it's because the sparkle is so reflective. It does not read like glitter at all and nothing migrates from the lips.