I found a really thoughtful guide on the official boards that I found very interesting to read. Partly because it's for a build I have, but moreso because it's just a really solid example of planning an IO build. It's specifically talking about Fire/Fire tanks, but the way he explains it gives a great format for planning any other IO-slotted toon. He goes through a deep analysis of every possible set bonus he can obtain, then looks for common ones he can maximize for great effect.
Anybody who's not cynically pre-judging IOs as 't3h l00ts' should take a look. It's well-written, and gives some great ideas for planning your new build.
http://boards.cityofheroes.com/showflat.php?Cat=0&Number=8130823&an=0&page=0#Post8130823
I also stumbled across this little gem recently - a nice guide for one of my main toons!
http://www.freedomreborn-coh.com/ar_spud_botstraps.php :P