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