sometimes,
online poker tells are really dependant on what the person is doing. for example, i was multi tabling, and was stuck at a table pondering a decision for some time while it was my turn on another table. when i came back, saw Q 10 of clubs, and raised 3xbb, everyone folded, and the bb said he folded 9 9, and that it was so obvious i had KK or AA. lol. what bs.
i think a nice little online tell is when a player bets wayyyy too much. to quote a instance that happened to me, i was in a .5/1 nl deep stack game in the bb with 4 4. the button, who was about even, $200, raised to $55. the sb folded and i was wondering, what on earth is he doing? he has been pretty passive the entire hour i was there, check calling, makin standard raises in position, and out of the blue he raised $55. it occured to me that he MIGHT've put in an extra 5 when he was actually only trying to raise to $5. and i was convinced it was a button steal when the accident occured. so i raised him $150 more, leaving myself with $120 behind. he called time, it ran out and he folded. before he left, i asked him if he put in an extra 5 by mistake and he admitted it. yups.