Man, I forgot how many mods there were for 42. Not quite halflife standards, but definitely getting up there.
I played tons of EoD, Silent Heroes, Desert Combat, and Galactic Conquest, all fantastic mods.
I also tried out alot of smaller esoteric ones that didnt last too long, but had cool ideas and worked well in the engine. I can't recall any of their names, so ill just give descriptions.
-Warhammer 40k mod. Play as space marines. Drive around in predator tanks with twin-linked lascannons. Cool.
-Post Apocalypse mod. Shoot people with rebar launchers and sawed-off shotguns. Had some awesome weapon and vehicle ideas. Totally mad max.
-Transformers mod. Pick a class. Use class to transform into vehicle (soldier=tank, scout=jeep, ect ect). Awesome.
-Medieval mod. Use swords, spears, and arrows. "drive" catapults and horses. This is the mod fh1 got the idea of "shotgun" melee weapons from. So blame them for uber-knives.