For everyone who is interested in rebuilding their Powerbook Duo batteries, check out these suckers:
http://www.mittoni.com.au/catalog/product_info.php/products_id/1838
Does anyone know if these actually exist? I've heard that the highest capacity 4/5A batts are 2100 mAH.
I was going to make a custom 2300mAh battery pack with 8 AA NiMHs from eBay, hoping it'd last longer than standard, but looking at that link, hmm.....