This morning on Simply Quilts the guest showed a tip for makiing 1/2 square triangles quickly. Low and behild I have been doing this forever, but I will share with you if you don't do this. I put a thin slice of masking tape (about 1/4" - I have 1/4" tape and it works great) on the 1/4" mark on my face plate. Then, instead of drawing from point to point on your stacked squares and sewing 1/4" away from the line on both sides, you just line up your point on the tape (top and bottom) and sew using your 1/4" foot.
I hope I have explained it well. Since I do it all the time I may not have explained it well for someone who has never done it.
This 1/4" tape works great for making straight lines too. Even with my 1/4" foot I sometimes get wonky seams, but having the tape there really helps me stitch in a straight line.