OpenTom is an open source wiki-based site that provides software for utilizing the Linux-based operating system in the TomTom One, 3rd Edition GPS device.
There are numerous kinds of software that you can use with the TomTom systems, most of which are actually required in order to use your TomTom devices. There is also some GPL that must be installed as well. The software is a closed source that you must purchase or comes with the devices. There are two main kinds of software for the TomTom, one of which is the kind that runs on a desktop computer and links to the device. You must create this one by taking the embedded software and running it through a programming environment.
If you're not so computer savvy, the other kind is run on the device itself, which entails running a tool chain on the linux operating system and ARM processor. Both of these can be a bit complicated, but are not too difficult once you've begun.
Disclaimer: This page includes links to alter the software included on a TomTom GPS device, which would void any warranty for further service to the TomTom.
TomTom Products
There are numerous products also made by the TomTom company and are all in the same GPS/navigation family. Some of those products are the TomTom GO, the TomTom ONE, the TomTom Rider, the TomTom XL, the TomTom XXL and the offshoots of each one of these. There are also multiple accessories you can purchase for the TomTom products, including OpenTom. Most of the accessories are a selection of antennas and receivers, most of which are wireless for convenience purposes.
OpenTom Software Demo
This YouTube video shows the OpenTom Software in use. Watch as OpenTom is used on the device.