I'm not so sure that there are any online tells, time taken to call, raise or whatever means nothing concrete unless a pattern is seen over many hands. How many times does the bloody phone ring when you're in a tourney, someone comes to your door, your AV update kicks in and hogs your CPU, if you have children in the house, add another 500 possibilities.....
If you play at the same levels most of the time and you start to see the same names, then note taking is the best possible weapon you can have IMHO.
Here I have to disagree with N.D. with regard to note taking, I include detailed summaries of specific hands in my notes and as much info as I can find as to a persons starting range with regard to their position, ok that's probably overkill at the micro level that I play at. But what I am attempting to do is define a range of possible starting hands for my opponent.
Say I've raised preflop with A, J off, one caller, flop comes 3, 6, 7 rainbow, I c-bet and the guy comes back all-in, if my notes tell me that he regularly plays 3,6 & 4,7 type hands, there's a pretty good chance that he's caught some if not a lot of that flop. He probably has at least one pair, he could have two or the straight or the straight draw, do I want to throw my whole stack in right there, and hope to hit an A or a J and possibly even still lose ?
My point is detailed notetaking, especially starting ranges I find to be more useful than notes that just say Donk!, complete spewtard etc.
I play low level games for fun against a friend who is a much better player and who taught me the game. I've also watched him play a lot so I can often name his hole cards pretty accurately (no I ain't Daniel, that man is a bloody GENIUS!), but for me, putting my opponents on a starting range/specific hand means I can often get away from hands that would have hurt me and also at times call donk raises when I have the best hand.
Also check hand histories, x mucks hand, straight into last hand/previous, what was he playing there, often it's a, holy crap he was playing 3c,5c on a diamond board with 3 overcards, valuable information and another note.
Oh, have I mentioned, I'm a fan of notetaking ?