I use two products for length and volume.
Currently, I use
Lancome Hypnose + Fiberwig mascara (this stuff is AMAZING..love love love it). btw, i've got super short..stubborn lashes..that point downwards GRRR!!!
For drugstore I used:
Nyx Doll Eyes Mascara in Volumizing. For me..it really thickens but also slightly lengthens. Or maybe it just coats my lashes so well that i find lashes that i never knew existed...or that my lashes were able to reach further? This stuff is really good for clubbing. Does not smudge, flake or run.