Great thread, thanks for the many interesting suggestions.
For Brazilian jazz, Quarteto Novo (s/t) on emi/odeon is indispensable (late 60's seminal group with Hermeto and Airto), as are the first two Airto albums on buddah: 'Natural Feelings' and 'Seeds on the Ground'. Again with Hermeto, Sivuca, Flora and Ron Carter.
Fairly obscure but marvellous is Walt Dickerson's 'Impressions on a Patch of Blue' on verve (with Sun Ra at the keyboards no less!).
Also somewhat under the radar is Paul Bley's 'Blood' on Fontana, with one Mark Levinson on bass! Fantastic trio record. Equally good, but perhaps more familiar is Chick Corea's 'Now He Sings, Now he Sobs' on solid state, with Miroslav Vitous and Roy Haynes.
Because no jazz list can be complete without blue note, a lesser known title not to be missed is Andrew Hill's 'Andrew' (with John Gilmore).
More to follow.....