https://en.wikipedia.org/wiki/GameTable_Online indicates it is defunct.
https://sourceforge.net/projects/gameniantabele/
Cursory Review 2018: Last version is from 2011, but project lead(who isn't a coder by his/her own words) still follows the site as late as 2017-11, but have no active developers. Seems to be downloaded every now and then. Review on page call it good, simple, fast to learn 5/5 star, 19 reviews
Gametable is a shared whiteboard client optimized for the tabletop gaming experience. It is written in Java to offer broad cross-platform support.
Gametable holds simplicity and ease of use as it’s highest ideals, while still supporting the needs of the game. The learning curve with Gametable is virtually non-existent. Gametable comes with pre-installed image sets, enabling the immediate creation of custom content.
Among the included features are Dice-rolling, Dice macros, Rulers, Tiles and Avatars-called Underlays and Pogs, Simple drawing tools, and Simple Card deck support.
Best of all, Gametable is Open Source, and is free for all to download, use, and enjoy!