Kent yeah I do agree with you but this only works sometimes. The quick check often times means someone clicked the check/fold button and usually fold to any bet. The problem with online play is that so many people play multiple tables, have connection issues or other distraction you cant see that taking time on check doesnt always have something to do with their hands.

As for counterstragies, I am guilty of using the check-fold button myself which I probably shouldnt do.

Great post. I pay lots of attention to speed. It's important first to find out if any of your opponents are multitabling since that distorts things.

BASIC RULE--For both live and online, I give more weight to their action if they take a long time. If they think awhile and bet, I'm more likely to assume they have something. If they wait awhile and raise, YIKES. If they think and just check, I assume nada. I'd say this is 75% accurate.

Other tells:
If they wait awhile to decide to call your turn bet when a flush card just fell, well you know they don't have the flush. They're trying to figure out what to do because they fear the flush.

Say I have TPTK and bet the flop strong and my opponent thinks and then makes just a call. I feel pretty sure he's on a draw from here out, and I play it accordingly.

Another tell is just the rhythm of the game (perhaps more in 6-max). People get in a habit of taking about the same amount of time to check when they don't have a hand. They are basically waiting for good cards and when they don't have them they are prone to make up their mind quickly and check. Hence, pot steal opportunity. The opposite is true when someone all of a sudden breaks their usual rhythm and bets.

Other people interpret waiting just the opposite. IF you have a monster try waiting a while before making a call/raise. Most people assume you are weak since most people with a strong hand and chompin the bit to bet or raise.

Counter Strategies:
Vary your own pace and you send subconscious messages. For example, say you limp with a SC and the flop is checked. The turn is a king. I might pause and then make a 2/5 sized pot bet. You'd be surprised how many people give you credit for the king.

Another tactic. Flop a monster and overpair guy bets the pot and you take a while to call him. On the turn, he checks and you check. He now thinks his overpair is good again and you have "confirmed" his suspicious that you were weak on the flop after you took your time calling. On the river, you'd be surprised how many people will play for their stacks. They can't do the U-turn and give you credit.

I use a poker site whose user interface sucks so badly that it's impossible for me to bet or raise an exact amount quickly...

And when I'm on the other site where the UI is awesome (FTP), I make sure I always type in the bet / raise amount, even if it's already in there, just to be consistent. Even if I'm just going to call, I fiddle with the bet amount thinking about a raise, then call. (Hey, it's as close as I can get to emulating Gus Hansen fiddling with his chips every time the action gets to him! )

I recognize that speed of play can be tinkered with, though, especially slowing down play, so I don't really trust it as a "read".

I guess I focus more on the rhythm of play. I agree with Trodgers that most of the time people have decided on their bet before it gets to them and you can get a feel for the rhythm or pace of the game. When that is broken, I think "oops, something woke him up".

2 other ones

long pause followed by a check--> usually nothing or a weak draw
insta reraise trying to scare you away usually only a semi strong hand