|Unity dash - displaying matching man pages as you type|
|Yelp displaying selected man page|
Manual Pages Lens package is available from my PPA. It can only be used in Ubuntu 11.10 at the moment since Ubuntu 12.04 (currently in beta) uses a slightly changed API and I haven't yet ported my lens to it.
By the way, if you don't want to or can't use my lens, you can still open manual pages with Unity dash by hitting ALT+F2 and typing 'man:' followed by a name (e.g. 'man:printf'), and it will bring yelp. Very handy.