1) 'Convert Newlines To BR' user preference
2) 'Link Display Format' user preference - governs link targets
3) Automatic URL conversion in posts (with a user preference to control this)
3a) Some support for 'izCodes' (*snicker*):
user ://somename [link|/forums/render/user?username=admin|admin]
post ://post# [link|/forums/render/content/show?contentid=52261|Post #52261]
These don't use [] around them (yet). No user preference for turning this off yet either, sorry.
Post bugs here, please! Thanks.