The icon kit is very nice (and I might get an additional one to complement my older OG keycap set). That said... how about icons for the rest of the keys in the nav cluster? (Insert, Delete, Home, End, Page Up, Page Down... and... Print Screen, Scroll lock and Pause as well)
I dream of having a keyboard with no legends on mod keys (except for F1..F12, obviously). This would be a great chance to standardize the icons generally used - look at Ellipse's F77 project for a great example of this.