House Rules

Businesses
http://blogofholding.com/?p=6738
Specifically, changes to the income earned in businesses.

Reputation and Sanity
Pages 264-266 of the DMG
Each PC has a Reputation (effectively Honour) score with the Thieves Guild and their peers, which is affected by their actions.
Additionally, everyone has a Sanity score to avoid going insane from horrific things. If a PC is subject to, and surpasses, lots of sanity rolls, they gain an additional point of Sanity, usually on level-up.

Leveling and Retraining
Page 131 of the DMG
Costs to gain levels are as per the Training rules. Retraining subclasses and feats are possible with an appropriate amount of time and money spent.

Short and Long Rests
Page 267 of the DMG
Gritty realism rules: a short rest is 8 hours, a long rest is 7 days.

House Rules

The City of Kazad OblivionGate