The only online tell besides chat that I know of is how long someone takes to decide to bet. A number of non-hand related factors can affect this (dropped cigarete, important phone call, etc.) but I've tried to notice patterns in villans' play
I tried using it in reverse yesterday. I play aggressive and the decisively, betting almost immediately in most cases almost all the time but had one interesting hand in a tournament at 5dimes:
blinds at 30
Preflop: Hero (2520) is CO with As, Ad.
Hero first-in raises to 120, SB (3500) calls $105 BB folds.
Flop: (170) 3s, Qs, 7s (2 players)
SB checks, BB checks, Hero bets 120, SB calls
I had top overpair and a nice 4-flush draw.
Turn: (290) 5d
Hero bets 150, SB calls
River: (440) Ks
I had him on Qx, possibly QJo and with all higher spades but my ace out, I employed my false tell strategy, waiting until time was almost up to bet, and hoping he had a spade as his high card, then,
Hero bets 170, SB raises to 600, Hero reraises to 1200, SB (crying) calls
Showdown: SB Qs10c
Hero wins 1640
Don't know if that was +ev but it was nice practice