Yarn Over (yo) - the easiest increase that leaves a little hole
Knit Front Back (kfb) - knit twice into the same stitch
Purl Front Back (pfb) - purl twice into the same stitch
Make One (m1, m1l, m1r) - add a stitch in between two others
Make One Purlwise (m1pw, m1lp1, m1rpw) - for increasing on the purl side
Knit Front Back Front (coming soon!) - like a knit front back but it keeps going!