Because I could.
At the time I was heavily involved with telecom network synchronisation, so I set some of the stuff up at home to play with it when I wasn't away on site.
I haven't seen many GPS synced clocks, and the ones I have are pretty much focussed on providing the sync for network time protocols. Most of the GPS stuff doesn't work too well indoors, they need external antenna feeds.
If you're a bit geeky I can show you how to set this stuff up, but if you're happy enough to simply synch a PC to the global time network look no further than stdtime.gov.hk.
Software for Synchronization of your Computer
dot.zen