Before I head off to bed, here's a link for now:
http://terra-arcanum.com/downloads/
High-res mod and many others. :)

The latest unofficial patch on the post above is outdated..
get latest version here:
http://rpgcodex.net/phpBB/viewtopic.php?t=39612

Nice one! So what mods to you recommend to someone looking to fix things up visually but not alter the gameplay (aside from addressing bugs and finishing work on incomplete quests)?

I also recommend: High Quality Town maps:
http://terra-arcanum.com/phpBB/viewtopic.php?t=15119&postdays=0&postorder=asc&start=0

Arcarnum WIP perhaps?
I also think Carnacum was released by a dev member.

Here's the straight link for the "WIP"-mod mentioned above:
Forgotten Places of Arcanum (A:WIP):
http://terra-arcanum.com/index.php?section=factory&content=awip&id=forgottenplace
edit: ...and because you don't want to register, use this link for download (changelog is still in the first link):
http://www.terra-arcanum.com/downloads/arcanum/rroyo/AWIP6.0.exe
And by the way:
Does anyone know if these mods and patches works nice with each others?
Should we use some exact order when installing them?

There's one other mod for Arcanum I HIGHLY recommend, if you don't have something else that will do it..
The level cap increase, which can be found here:
http://www.terra-arcanum.com/downloads/ under 'hacks'
Basically the official cap is 50.. my half-ogre fighter was 50 by half way through the game...

Yeah, the level cap was annoying if you played a fighter-type. Since you got experience for three things: Completing quests, killing enemies, and hitting enemies, if you let your followers fight for you, the level cap wasn't a problem. If you fought your own battles and didn't use the trains or Teleport spell to get around on the other hand.
Hitting the level cap a third of the way through the game took a lot of fun out of it...

But isn't the problem more in generous XP rewards rather than level cap. Game tend to become cake walk around halfway even with the standard level cap.

Hmm that's a good point. Though with the tech or magic trees in this game as well as skills, there was plenty of interesting things to use those points you got on. And the game did indeed get easy after a while, though melee was not nearly as broken as magic (since that first Dark Necromancy spell is all you'll ever need in the way of combat spells, because it increases with your magic rating). Still, I remember starting several combats by it being my turn and me slaughtering every single enemy before they could get actions in. Of course, that was part of the fun :)