GURPS was actually one of the first RPG systems I learned back... oh... a hundred years ago. As such, though I haven't played it in probably 95 years, it still holds a soft space in my heart. If you're wanting more content for the game (and the million different worlds it inhabits), you'll want to check out the Pyramid campaign up on Kickstarter. It's a webzine all about it from Steve Jackson Games.
From the campaign:
Pyramid was the monthly PDF magazine for serious gamers, created by serious gamers. Each month, Pyramid delivered articles about a specific theme, from modern-day superheroes to post-apocalyptic gaming to magic on the battlefield. Most of Pyramid's articles are either generic, suitable for your game system of choice, or designed for GURPS, one of the best choices for serious gamers for over 20 years.
During the magazine's PDF run (Volume Three), each issue of Pyramid was devoted to one of three general themes: past, present, and future.
Now, with your support, we're launching the newest incarnation of this gaming magazine! Pyramid Volume Four, if this campaign is successful, will continue where the previous volume left off – with three new PDF issues covering the three classic themes of past, present, and future.
NOTE: This campaign is for three new issues only and is not a promise of any issues beyond those produced as part of this Kickstarter project. If there is enough interest and demand, we may return to Kickstarter in the future to expand Volume Four beyond these three issues.
The campaign's closing in on 20x funded with only 5 days left to go.