BitNami
bitnami.org provides native installers, virtual machines and Amazon cloud images for popular web applications, including Trac. Among the many self-contained "stacks" - as they call it - there is a Trac stack which makes installing Trac with Apache and Subversion very straightforward. There is one for Windows, Linux and Mac OS X that includes everything necessary for having a complete installation up and running in minutes. All of the stacks are freely available and can be used for both development and production purposes.
There are also VMWare virtual machines and Amazon EC 2 Trac cloud images. Combining one of the Trac Amazon images with the Amazon Free Tier it is possible to host a small server running Trac in the cloud completely for free.
BitNami also offers a commercial service, BitNami Cloud Hosting, that provides monitoring, backup and management services for instances hosted in the Amazon cloud. This service supports Trac and also has a free tier.