Holy crap I love this! Thank you so much for making this simple, elegant sheet. I do have a few suggestions though:
Add lines to the feats/magic items section, and to the Race/class abilities section.
Add lines to the equipment section, with a small column to the side for weight. Perhaps divide the block into two columns to fit more loot, leaving the bottom line open with a "total weight" entry.
It might be best to move the "Healing surges used" box closer to the "Healing surges" box (there's a perfect space for it under passive perception). Fill in the now-empty space under HP with bigger "Max HP" and "Bloodied" entries.
Make the stat mod lines actually line up; it's a bit more aesthetically pleasing that way. Same for the skills list.
Ok, so that's more than a few I guess, but they're mostly aesthetic; this sheet is great as is.
Mor
