Sweater Wizard is excellent -- I'm not sure if it's available for Mac though. I went to a workshop at my LYS that was a how-to on all the features, and it's amazing. Like it'll tell you how many yards of yarn your pattern will use as you configure it -- very handy.
Knitter's Geek Code
KCR+ Exp+ SPM+ Steel+ Bam+ Addi++ Pl-- Wool++ Cot Lux+ Stash Scale+ Fin !Ent Int FI> Tex Lace Felt Flat Circ+ Dpn- ML+ Swatch+ KIP+ Blog+ SNB> EZ? FO+ WIP3 Gauge W+ Alt Sw