For me 1 tiny mutator I have has become notable in that I run it with every other mod and mutator.
Xanth-Realism http://www.ut99.org/viewtopic.php?f=3&t=4773
It does not offer a major change in game-play, other than projectiles will turn you based on where you hit.
Small-damage, rapid-fire now becomes as defensive as it is attacking. You can make it very difficult for someone to get a clean shot back at you.
Extra physics is applied to the empty shell-casings and the hand around longer, and become movable, so they get kicked out of the way as you walk over them. This also can be heard by your enemy

Sounds awesome in a fire-fight with loads of brass rattling around. You can almost smell the gun-powder

There have been a few updates and addons for relics.
Some add new relics, some add new features.
Wormbos Enhanced Relics, replaces the relics with a framework to manage relics in.
It also adds some new relics and tweaks some of the originals. Also available for this, he ported a bunch of Quake team pickups.
Relics 2, adds 9 new relics, some of which are similar to the originals.
Relic Classes is very interesting alternative. This gives everyone all the original relics, and you cycle them instead of throwing away. Only 1 relic can be active at a time.
Predator/Blink Relic makes you phase in and out of visibility (with the spooky predator cloaking sound

Wrath's Relics 3 very powerful relics.
DOWNLOADS: http://my.opera.com/Unreal-Tournament/b ... nd-pickups