David Lindley is crucial. Ry Cooder likewise. David Gilmour uses lap steel for a lot of atmospheric effects on Pink Floyd's records. See, e.g., "Breathe" on DSOTM.
Greg Leisz is not strictly in the blues/rock world, but plays some amazing stuff that originates in the blues.
Check him out with Dave Alvin:
[youtube]H5mmpTzxCSI[/youtube]
AJ Ghent is a newer arrival on the scene. Here he is singing and playing steel on Sam Cooke's classic, "A Change is Gonna Come":
[youtube]bsA24mofVLw[/youtube]
Steel solo starts at 2:38 or so.
Brendon McNichol of Queens of the STone Age does some heavy stuff with a steel guitar.
Consider also Derek Trucks, who plays conventional guitar, but in open E tuning, so you can start with working out what he does, playing overhand on the lap steel.
For more names you can research on your own, see https://en.wikipedia.org/wiki/Lap_steel_guitar#Notable_players