PBLang is the best php non-sql forum system ive ever seen. Installation really is painless, got my board up and running within 10 mins. The admin control panel does the job very well and the boards look and feel can easily be edited to your needs. Features on PBLang are similar to what you would expect with the big guys such as phpbb: members list, searcher, personal messaging, stats on the main page, bbcode etc... and still it doesnt need a database!
I think the major selling point on this script is that the board is in many langauges so that people from around the world can have a online community in their prefered language. Plus the support in the forum is good.
A little hitch is of the displaying of the user info in the url, but you only see it when you submit on login. and nowhere else. ;o)
Other than that its a great product, im really pleased with my board and i know of people who like the board just as much as i do :-)