Hmmm.... I don't have any calluses on my hands, and here's why... 1. I use a LARGE table just for the kb and mouse, and spread out all over it (with a separate table behind it for my computers and monitors). 2. I don't use a mouse mat. I use a graphic artist's cutting board. Measures 30 x 40 cm, costs about $10, and NEVER wears out. 3. I use the kb whenever humanly possible. Of course, I do have a large callus on my butt from sitting here all day. Does that count? mac PS Don't panic! I'm not going to post a pic of it. LOL.