Is there a way to check who is connected to my Galaxy Nexus hotspot
Install Wireless Tether app (free) if you are rooted. It features Access Control. Means, you can use it to allow/deny ad-hoc clients for mobile data. Ofcourse, for this.. it'll need to display connected clients.

And, it works with Galaxy Nexus LTE!

Update:
You can use Fing - Network Tools, too. Its clean way for your task.