MapBox

TileMill is a tile rendering engine designed to create map tiles leveraging existing open source GIS tools and the power of Amazon's cloud. In short, TileMill can process data uploaded as shapefiles or raster images or integrate with a PostGIS database. It then generates tiles based on custom style sheets and custom graphics for markers and symbols. TileMill supports fast, multi-process uploads to Amazon S3, from which users can instantly distribute data through Amazon's CloudFront CDN.

Version 1.0, the most current version, has two parts. First is the TileMill server, basically an AMI (Amazon Machine Instance) that will boot up a preconfigured tile rendering server. If you are new to working with Amazon's virtual machines you should read Amazon's Getting Started Guide. You will need to download the TileMill Tools, the second part of TileMill. The tools run locally on your machine and allow you to submit and track jobs, and control instances. Windows, Mac and Ubuntu Linux are supported.