This is basically the same question as posed here: Increase vibrate strength
I thought there might be a different answer for the Nexus 4, however, seeing as how it's a different manufacturer and the OS has changed slightly.
I came from using a Nexus S which had a really good vibrate. With the Nexus 4, however, even with nothing else in my pocket sometimes I can't feel it. I'm used to being able to get a slight buzz or something if I set my phone down on my desk but with the Nexus 4, the best I can hope for is a slight buzz if it's on a hard surface. Touching papers or something else? Better hope you were looking at the phone, otherwise you're going to miss incoming calls.
For other Nexus 4 owners, is this a noticeable issue with your phone? Maybe mine is slightly defective. If not, is there any way to boost the intensity or strength of the vibration through settings?
I've seen that the Galaxy phones have a vibration setting that can be adjusted but I can't seem to find something similar on the Nexus 4.