Generally while I am playing I have a pot of coffee brewing and a very large cup in front of me so yes I do get a bit tweakish while I play...
But on to what you meant...
I fit my tweaks into two categories... the first being the ones I use almost every game.
These are things like raising the party size per point of leadership to 7 instead of 5 (only gives 20 extra men at max)
Arrows/bolts to 50
All thrown to 10
Tavern keepers buy prisoners
Meet the guild master (I get lost too much to not use this)
Meet the village elder (same reason)
Decrease the time it takes to read a book to 72 hours
Battle Continuation
And thanks to the new TweakMB the select quest option (I LOVE THIS)
Increase exp from 2.0 to 4.0 (no that does not double the exp gained...)
Double the tournament bet amounts
The second list I just use for goofing off this includes things such as:
Exp set to 10.0
arrows/bolts set to 500
repeating crossbows
arrow/bolt damage increased to some random number (usually gets 100+ damage instead of 2 or 3)
not really a tweak but set all my attributes to 999... that can be really fun
set all skills to 15 max instead of 10
and my work in progress... epic armor tweak... I edit all the armors to be half the weight they currently are while offering 3x the protection... this one needs desperately to be combined with my arrow/bolt (and thrown) damage tweak above or it will take forever to kill people