I may be a bit weird in this regard but I NEVER tip with my card due to some paranoia that The Man keeps it and the little guy will never see a penny of it. Also I never leave it on the table either, I put it in their hands to insure that the person who earned it gets it.
Oh and also the last time I left a tip on the table I happened to see some random waiter swipe it up as I went back to get my jacket, I didn't say anything but never again...
As far as tips on credit cards go - the server always gets any tip left to them. If we're required to tip-share at the end of the night that comes out of our money. I.E. I have only Visa cards for 4 tables, all leave tips on their cards, I get cash from our bartender equal to the total tips left. I then tip the bartender 1%, the busser (if we have one) 1%, and our expo (again, if we have one) 1%. The kicker is that I have to claim all the credit tips (it's tracked by the computer) for tax purposes when I clock out (even the tips I gave to the other staff) and then they are also supposed to claim 100% of their tips for tax purposes (so the money is double taxed right from the start). As for other servers picking up someone elses cash tips I would make sure that person was fired. There's an honor system amongst servers and you don't mess with the system. Now if they were taking the tips to the other server that is fine, but you have to be some kind of lowlife to steal from your fellow workers.