""new" artists that have been around for a long time"
I hate the terms "mainstream" & "underground", but listening to "U" from Black Milk's Popular Demand today I totally forgot it featured Ty & Kory. The same Ty that went on to be Ty$ aka Ty Dolla $ign of Toot It & Boot It/Paranoid/Or Nah fame.
Most folks that rock w/Ty$ don't remember Ty & Kory.
Also made me think of Miguel, who not only was all over the LA hip-hop scene with folks like Blu/Exile, but had his song "Getcha Hands Up" on 106 & Park. Hell, dude was even on Fatty Koo which few folks remember.