Autotracer.org - Free online image vectorizer
Faviconer - Faviconer.com, or favicon generator, is online tool for creating favicon.
potrace - Open source program that transforms bitmaps into vector graphics.
ConvertIcon! - Converticon is a simple icon utility.
Vectorizer.io - Fast and easy way to vectorize an image online
Ordinatore - Those who want to tidy up their Macs will surely love this application.