*Floater*
Contributor
[WARNING: OLD THREAD]
If you are still looking for a something to warm the hands without requiring thicker (less agile) undergloves, you could try Heating packs. I've done a few dives using the Hot Hands brand packs between thin silk liners and fingerless polartec gloves; wristies. I'm still deciding on them, but the idea seems solid for someone who wants minimize glove thickness. The packs cost about $1 a piece, or less if bought in bulk, and are good for about 8 hours. The ingredients produce heat when they react with air (oxygen), so they might burn out a bit faster if using nitrox for drysuit inflation, and probably not at all if using argon. But for most people a pair should last for the day. And they won't explode if wet, though that probably reduces their effectiveness.
