Funny story. I've had my Nexus 4 for 2 months without a SIM card because:
1) My last day of my Sprint contract was 12/31/12,
2) But didn't find out that my actual last day of service was the 13th of January, until the last minute
3) Procrastinated calling Sprint until 2 weeks ago when I canceled my service and then asked about the number porting and they said my service had to be active to do that, so I had to cancel the cancellation... I know, ridiculous.
4) Now my last day of service will be Feb 12th, so I will activate my T-Mobile SIM a week before the 12th and then port my Sprint number to Google Voice when my T-Mobile service becomes active.
They really do make you jump through hoops to figure out when your true last day is, or if your bill is prorated when you cancel mid month (it's not), or whether the billing cycle is a month behind or a month forward etcc..
Hopefully T-Mobile prepaid will work out well for me. Anyways lol I got a little off topic.
I've been using my Nexus 4 without the SIM for all the things my phone does except for calls, I use GVoice on my Nexus 4 for texts. I use it as a remote (unified remote) to control my laptop when it's connected to the TV, or to control MediaMonkey when I'm listening to music on my laptop (MM remote). Also was using Youtube remote for my PS3 the other day with my N4. I use google+ messenger to keep up with family. I use the flashlight instead of the one on my phone, because it actually turns on when I want it to.
I do all this with the Nexus 4, not because it's convenient. Because having to charge 2 phones and a Nexus 7 is definitely not convenient. But because my Epic 4g is just too damn slow (w/CM10) in comparison. I haven't had any hiccups on the N4 it's so friggn fluid, definitely the best phone I've owned. And a lot faster and more responsive than my Nexus 7!
I cannot wait this week when I can finally say Goodbye to my old Epic and Sprint. And say Hello, to slashing my bill 2/3's while having the best damn device I've ever owned.