Hobbit compatible temperature monitor

I am looking to add temperature graphs to hobbit.

What should I use to monitor and graph the temperature of our server room?
None of our servers report any temperature readings in the client data.
We have some APC battery backups that have environmental monitors built 
in, but I am willing to spend a little cash on a separate device if 
there is something proven to work with Hobbit.

Thanks,

-Eric