Pygmy Sunbird (Hedydipna platura)
Male. Characterized by the green head and bright yellow belly. The streamers get even longer than seen in this pic, about doubling this bird's size from 9cm to 17cm (3.5 to 6.7 inches).
Outtake from The Gambia. Until I started running down the BirdsGS index and found no Pygmy Sunbirds on Flickr. So an FBW newbird as well.
These shots taken near dusk, and I foolishly did not adjust the ISO. Still, they'll serve for now.