Besides the obvious....
LS.com (search the archives here).....
You can try the following sources for information:
-Your local paver supplier or stoneyard
-Any of the paver manufacturer websites (most have good info)
-http://www.tmac.clara.co.uk/paving/home.htm (a site from the UK with some good stuff in it)
There is also the ICPI (interlocking concrete pavement institute) which still has not givin me the chance to promote them in any way shape or form. I couldn't even get an info pack out of them last year when we tried (and stressed Lanelle out too!) But they're there also.
Hope this helps a little more, sorry it took so long for a real reply.