Rules Differences at Online Poker Rooms

[holdem17]

Hello,
I just run into a rule difference on Absolute Poker, that makes me wonder if there are other rules variations that I should be aware, to know how to play optimal in this very rare circunstances.
The difference I detected on Absolute Poker, is that if player A raises 6.50, player B calls, player C has a 6.60 stack and goes all in (raising 0.10), now player A can reraise any ammount he wants !!! [img]/images/graemlins/shocked.gif[/img]
Is somebody aware of any other variation in the rules at any of the online poker rooms?
I think these subtle differences can be very very important in certain circunstances to make the right move, and can give a small edge on these circunstances to the player familiar with the local rules.
TIA & Regards ...