Is there a chip similar to the TLC5940 that is compatible with common cathode rgb LEDs? I made the mistake of purchasing common-cathode LED's before I completely understood the LED driver. I would prefer a model manufactured by TI such that I could get a free sample. If not ill have to purchase new LEDS since they cannot be returned.
I don't have a reference book handy, in front of me, but.... have you looked to see if, perhaps, the TLC5941 happens to be a common-cathode PWM LED driver?
probably an even-money bet that it is...
It is not, it's a sink driver like the 5940.
Go figure... haha
I just ordered 100 RGB Leds Common Cathode as well, and bought a few 74HC595 not even thinking about it..
I read up on the ShiftOut tutorial.. this'll be my first time playing with shift registers, so hopefully it's semi-simple!
But best of luck, I'll be checkin back here to see peoples input! Hopefully there are some simple/cheap solutions! I searched connecting common cathode to arduino.. lol nothing useful.
The 74HC595 can source your LEDs just fine.
Woot!
So many.. questions.. but, hopefully I'll be able to answer them myself after I burn a few LEDs/Shift Registers lol 
Actually I've done fine so far with hooking everything up, it's code issues for me.
But that gives me time to learn before they get here I just want.. controllable pretty-colored LED's, I'm assuming I'll only be able to use 3-4 RGB LEDs with the 595, but that will do just fine!
Will the STP16C596 be able to perform the job and will I need series resistors? I am looking for a chip that will still be able to dim the led. (I think that is done by turning on and off the LED really fast right?)
Will the STP16C596 be able to perform the job
No it is still a constant current sink (it says so in big letters at the top of the data sheet).