Not online CBT (I did try a free online CBT site & couldn't get on with it)..
books, yes!!
I've bought quite a few self-help books but the only ones that I've found readable (he's got a great sense of humor and writes in a very engaging way) and extremely helpful are the CBT books of Dr David Burns. I've got nearly all his books as I just enjoy reading them, I would recommend them all, but especially:
'The New Mood Therapy' - the first CBT self-help book ever written, the most prescribed book by USA therapists for their patients.
'When Panic Attacks' - has some of Dr Burns latest CBT techniques (he continues to develop newer & more effective, faster working CBT exercises, as professor at the Department of Psychiatry and Behavioral Sciences at the Stanford University School of Medicine) which work for anxiety and depression.
'Acceptance Paradox' technique in this book is now what I use weekly and it's amazing! Can turn me from very depressed to almost depression free in minutes! (he includes a depression 'Burn's depression checklist' so you can see how depressed you are, I photocopy them and fill one out before and after doing the exercises, to check my progress).
You're basically getting some of the best help you can get, IMO, and that's as someone who has been suicidal in the past.