Vectorizer.io - Fast and easy way to vectorize an image online
Img.vision - Image hosting & video hosting for eCommerce sellers
RasterVect - Professional raster to vector conversion program (vectorizer).
UploadHouse - Thumbnail and resize your photos and images
potrace - Open source program that transforms bitmaps into vector graphics.
ImageVenue - ImageVenue is a great online hosting service that allows uploading pictures for showing creative works with a simple-to-use technique.