Here are few of more popular grips I've seen recently:
-[b]Duckbill grip[/b], $8
No grooves, has extended tongue that fits under the rear of the trigger guard (a la the gapper)
-[b]Stowaway grip[/b], $13
Storage area with hinged floorplate; A2 profile.
-[b]Hogue grip[/b], $20
Rubber surface with finger grooves.
-[b]Falcon Industries Ergo grip[/b], $22
Available in right/left/ambi versions; has subtle finger grooves and textured surface.
-[b]First Samco[/b], $24
See above.
-[b]Sierra Precision Rifles, SPR grip[/b], $28
Large grip with groove and thumb shelf, smooth surface.
-[b]Tango Down Battlegrip[/b], $30
No grooves, storage space is designed for various battery sizes, includes spacers. Smooth and textures surfaces available.
Prices shown are approximate retail.
Again, this is by no means a comprehensive list, just what I've seen lately.