Battlegrounds: RPG Edition (aka BRPG) is a virtual tabletop program that has solid GURPS support (although not much in the way of automation, beyond turn sequencing). Hexgrid with snap-to-grid, support for character facing, GURPS-compatible figure and animal bases, etc.
Below are some convenient links for anyone wanting to prepare a GURPS game using BRPG:
Dice macros for playing GURPS.
Custom text labels that are useful for playing GURPS.
Turn Sequencer settings for GURPS. This allows the turn sequence to be auto-sorted based on things like each combatant's Move, Basic Speed, DX, etc. (both 3E AND 4E rules are supported)
A pre-made Gladiator Arena which should provide a handy way to try out GURPS combat.
(Note that some of the links I posted here might only be accessible to people who have registered on the Battlegrounds forums.)