Some of the comments on yesterday's post got me thinking. It would be perfectly possible to run a game of D&D and using its core themes (bunch of adventurers seeking glory, wealth, fame and fortune through exploring ancient tombs and ruins and hexcrawling) in a setting with more up-to-date technology - taking inspiration from, say, the American Wild West, Brazil in the era of the bandeirantes, the exploration of Australia's interior by whites, the Russian conquest of Siberia, Livingstone's journeys in to "darkest Africa", and so on - but with dragons - were it not for the fact that D&D as a system just doesn't model guns very well. You can explain away the fact that 9th level characters have so many hit points by abstraction in a normal game of D&D, but the abstraction gets stretched to breaking point once it comes to bullets (this is part of the reason why I loathed my experience playing d20 Modern, despite perfectly good DM and players).
There is a simple solution to this, of course: as characters gain levels they don't gain hit points. A 9th-level character has the same number he started out with. (The DM might want to be generous and give starting characters max hit points for their class.) So an ambush of 9th-level characters by shotgun wielding goblins would retain the sense of fear and danger that a real gunfight would have, and make things suitably concrete.
Another thought occurs, however: Cyberpunk 2020 is a surprisingly robust and effective generic system if you want something that is easier to learn than GURPS while retaining a decent level of grit and crunch. I know this because I ran a WWII-era zombie game with it and thought it worked very effectively. (The only complaint would be that dice rolls are irritating and fiddly when it comes to damage - if you get hit by a 7.62mmx54mmR round you have to roll and add up 6d6+2 damage, which is clearly enough to render an unarmoured target dead in almost all cases but not quite enough to justify saying 'a hit is a kill', so in big gun fights you are constantly rolling and totalling up fistfuls of d6s.)
I also think that, the more 'modern' ones D&D becomes, the more it needs to have skills. In a low-technology world, people are not particularly specialised, because adventuring skills are not hard to learn: everybody can swim, use a rope, climb, pick locks, look for secret doors, etc. But the more technologically advanced a society becomes, the more career-type skills become necessary - it's more plausible to imagine somebody would have to sacrifice learning other skills in order to become a train driver, or astronomer, or demolitions expert, or whatever. A system that wants to model this would have to have a skill system, and Cyberpunk 2020 has a simple and reasonably effective one.
You would probably need to have some sort of wealth-for-XP mechanic on top of it, of course, but that would be easy to cobble together. As characters gained levels they would become more skilful, and the magic-users would get to use more powerful spells, but their basic physicality - their attributes and hit points - would remain the same and they would be as frail as ever in combat. I think this would be an interesting marriage between adventuresome exploration and hijinks and the constant risk of sudden death.