Any artists you try to get every recorded appearance by, both leader and sideman? For the sake of discussion, let's say there's a 10 record minimum here.
The only ones I can say I'm working on are Ran Blake and Jimmy Lyons, and I'd say I'm a little under halfway there with each. I chose these artists for a few reasons: first and foremost I think they're both unique, brilliant, engaging musicians, but I also think they never showed up on a bum record And with about 30 or less appearances, none of which are terribly obscure, I think this is doable.
Of course, there are plenty of other artists I seek 90-99% coverage of, but wouldn't turn the earth over for every last thing, a la some of Miles' more obscure bootlegs and 80s records, or some of Ornette's sideman appearances.