I know how you feel helpeskdan; I failed today with 781. This is the third Cisco exam I've failed on the first attempt (after passing CCNA and BSCI on the first go, I thought it would be a breeze).
I have several years of solid troubleshooting experience, and actually feel it's one of my strongest areas (as do others), but the CIT exam (and other Cisco exams) seems to go out of its way to confuse you, or make things harder than they need to be.
Whoever decided 'testlets' were a good way of asking a series of questions needs to be dragged outside and slapped around with wet fish. I was staggered there weren’t more 'real world' configuration troubleshooting tasks or more simulation stuff – surely this is more valid than the questions they ask?
For others taking the exam, you should really know how to interpret your debug output. You can argue that this is a very valid thing to know, and should be something everyone knows. I’d agree to an extent, but I rarely, if ever have to resort to using debugs on live networks (and who is going to remember what the output means when it can be referenced far more easily and accurately?). Nevertheless, it’s something I should have studied harder.
The links above are great – I’ll be using that as well as my BSCI Self Study book (single best Cisco book I own) to setup example labs etc. ISDN is something I wish would die a painful death, but it refuses to go away, so needs a refresher in my mind also.
Trying not to sound to down about this, but the more Cisco exams I do, the more I question their validity (whether I pass or fail).
Good luck!