Here are the ssk (slip, slip, knit) and k2tog (knit 2 together) decrease stitches. They are both worked over 2 stitches and produce 1 stitch. The stitches each lean in different directions and are very helpful when trying to maintain a design throughout your decreases.
The ssk is left leaning
The k2tog is right leaning.
You can jump the the stitch demonstrations:
1:19 ssk
2:22 k2tog
