I had the same though, and decided to just try a cheap'n cheerful HID style device.
The item below seems to work perfectly (for all small values of perfect)...
PC Computer Wireless Remote Controller with USB IR Receiver
(It looks to be very similar or the same as the Deal Extreme device above).
Furthermore it works with the similarly cheep'n cheerful Ralink Wireless card on the other USB port, on an unmodified (as in still with the factory fitted fuses) version 1 model B Pi running off the USB connector on my laptop, so no power issues so far.
DMESG shows the following...
[ 3.181011] usb 1-1.2: new high-speed USB device number 4 using dwc_otg
[ 3.308976] usb 1-1.2: New USB device found, idVendor=148f, idProduct=5370
[ 3.318423] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 3.328287] usb 1-1.2: Product: 802.11 n WLAN
[ 3.335089] usb 1-1.2: Manufacturer: Ralink
[ 3.341716] usb 1-1.2: SerialNumber: 1.0
[ 3.431060] usb 1-1.3: new low-speed USB device number 5 using dwc_otg
[ 3.544469] usb 1-1.3: New USB device found, idVendor=1d57, idProduct=ad02
[ 3.553826] usb 1-1.3: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[ 3.575628] input: HID 1d57:ad02 as /devices/platform/bcm2708_usb/usb1/1-1/1-1.3/1-1.3:1.0/input/input0
[ 3.591806] generic-usb 0003:1D57:AD02.0001: input,hiddev0: USB HID v1.10 Keyboard [HID 1d57:ad02] on usb-bcm2708_usb-1.3/input0
[ 3.614598] input: HID 1d57:ad02 as /devices/platform/bcm2708_usb/usb1/1-1/1-1.3/1-1.3:1.1/input/input1
[ 3.630092] generic-usb 0003:1D57:AD02.0002: input,hiddev0: USB HID v1.10 Mouse [HID 1d57:ad02] on usb-bcm2708_usb-1.3/input1
Bus 001 Device 004: ID 148f:5370 Ralink Technology, Corp. RT5370 Wireless Adapter
Bus 001 Device 005: ID 1d57:ad02 Xenta
.. and if I do a startx, I have an IR mouse, media type buttons, and a rather difficult to use keyboard (fine for media center applications, but since you type text style on it, i.e. several clicks for each letter, I wouldn't want to compose a novel).
The whole thing is in a small form factor similar to the Pi, the remote being about 2cm longer and slightly narrower than the Pi.
Not bad for £3.42 shipped (About $5 US).
I suspect most of these HID style devices should work, but I can vouch for the above.