I think an app that acts as keyboard and scans + types NFC tag IDs, like the KBR1, would be nice to have. A KBRApp.
There are multiple options to connect a HID, bluetooth and USB.
I think a bluetooth version would even be possible without rooting the device! (Cuz there are apps to act as keyboard.)
No, I don’t wanna develop it, but I’d pay $4,99 on the Play Store. 
Not to be confused with a KBRApp that types it into the phone (but that’s already possible with a rooted phone & NFC Tasks).
There are a few apps in the app store that can scan in the UID. It also adds the : so it isn’t the best I have found.
I also would pay for this keyboard app that worked better.
If you’re on Linux, you can use the SiRFIDaL server with the keyboard wedge client. It’ll do exactly that.
EDIT: nevermind, I just realized you were talking about a cellphone app. So, not SiRFIDaL 
Tasker will do it with the cellphone’s NFC reader, on Android.
“Configuring an Android device as an external NFC reader for SiRFIDaL”
Oh shi*t this is awesome! Y nevermind, this seems like what I wanted 
(just less convinient)
Okay, so… Let’s see if I understand correctly: you want to use a cellphone as a keyboard wedge for a PC? In that case, yes, SiRFIDaL will do it. But SiRFIDaL is more generic than just doing that, hence the added complication.
It’s not that complicated though
Yes you do understand correctly
Yeah sure, but a KBRApp that you connect as a second keyboard would be even simpler.
I went NExT for a reason, I wanted this ‘hacky’ stuff and I’ll def. get into SiRFIDaL! Still a KBRApp would be cool
Thank you!
Sure. I’d help you if I could, but I know zilch about developing on Android.