I know you said Ubuntu/Debian, but here are two cards I can recommend:
Silverstone EC03-P USB 3.0 PCIe (also sometimes known as the EC03B-P)
Silverstone EC04-P USB 3.0 PCIeI use the EC03B-P on my home Windows XP workstation. The drivers are minimal (as in no fluff/cruft or nonsense).
The EC03-P / EC03B-P are driven by an NEC uPD720202 chip.
The EC04-P is driven by an NEC uPD720201 chip.
I have no idea what the difference between the two NEC chips is.
You can dig through the Linux kernel source or dig up general hardware compatibility docs and confirm these chip are supported.
You might come across the
EC04 and consider buying it. Don't. The EC04 uses a TI chipset, while the EC03* and EC04-P use an NEC chipset. Many,
many reviews I read on the web indicated that a lot of people had stability issues with the TI chip and that going with the NEC chip solved their issues hands down. I didn't want to take any chances so I went with the NEC.
My experience so far with the EC03B-P card has been rock solid. Not a single oddity or anomaly.
P.S. --
Do not get a PCI USB 3.0 card! 32-bit PCI has a maximum throughput rate of 133MBytes/seconds; USB 3.0 can do up to 625MBytes/second. Be smart and go PCIe or else you're losing out on a very large amount of bandwidth.