Surface already comes with Wacom's digitizer technology so you can get pressure sensitivity and all that good stuff. You probably just need to buy the stylus.
Microsoft's own Fresh Paint app is another one that could benefit from this. One thing to note is that all of the Bluetooth styli released so far on iOS are exclusive to Apple's platform. An exception is Hex JaJa, which is cross-platform between iOS and Android, but it's not a Bluetooth stylus either - it utilises high-pitch sounds delivered via microphone.