bbPress showcase is a site dedicated to showcasing the power of bbPress (the forum software from WordPress developers).
Simple Machines Forum mod that allows you to submit a post by email to the forum
Light, clean and fast forum software
TalkPress VIP is a bbPress forum hosting service from Automattic / WordPress.com. Starts from $1'000/mth plus $1'500 setup. Application process, not all sites accepted, like WordPress.com VIP.
How to restore encrypted partitions on the ubuntu forums. Could be useful if needing to restore from a backup of an encrypted disk.
Nabble provide a forum front end interface to mailing lists. This is the rsync (hosted by samba) mailing list. Searchable, very useful.
VMWare Community Discussion Forums for VMWare Server, Player, etc.