For triangles go to www.quiltersrule.com and look at the tool called the Quick Quarter or Quick Quarter II. You can get them at most quilt shops and the directions are soooooooooo easy.
It is really as simple as cutting a couple of squares, drawing a couple of parallel diagonal lines, sewing a seam on each of those lines, cutting down the middle, pressing and re-squaring, and voila perfect triangles.
I love doing triangles now!