Improve resistance to fingerprinting
Per https://panopticlick.eff.org the system fonts and screen size/color depth are by far the biggest pieces of identifying information.
If you could get the most common list of system fonts from the EFF and use that or a small rotating set of common ones, that would be one less thing that could be monitored.
As a broader (optional) feature, perhaps a setting that let your browser window automatically resize by chunking to even numbers and 'standard' sizes instead of allowing things like 1037x824x24.
Trac:
Username: feature-requester