Is there a handy place to find some stats for characters like town guards, common criminals, an ordinary merchant, an 'average' knight, etc? Or do you spend the time to create a stock of these people yourselves? Am I, in fact, being lazy? 
The character templates starting on page 21 of the core rule book are adequate for a lot of characters. I just jigger some numbers around when necessary.
We've gotten a lot of milage out of the templates in the corebook, p. 21-23.
I think there are a few others here and there, but mostly I either build a full charactersheet, or use my extensive experiencesup[/sup] and just guesstimate something. 
There's also a fair number of stock character templates in Covenants. Other sourcebooks have a few as well -- I saw some in The Church for templars, for example -- that can be reused for different purposes with only minor alterations.
The Grogs book contains a huge number of stats at different ages for lots of character types.
If you need to improvise in a hurry - in general, I just assume they have very low charateristics and abilities of 5-6 for their two or three biggest professional skills and 2 in minor skills. This covers a lot of generalities. Give them a couple of personality traits at +2 as well.
Realms of Power: the Divine as well.
Mostly just the abilities though - no cahracteristics, flaws or virtues. Though there's plenty of information on how to flesh them out, and tools to do so quickly.
City & Guild has some information about the suggested Abilities and presumed levels of craft apprentices, journeymen, masters, and guild deans.
Otherwise just wing it, as people said before me. Assume a trained, adult professional has a score of 5-6 in one or more abilities he makes a living by, and 2-3 in secondary ones. Decide whether that person has a natural aptitude for his or her vocation or not, and assign relevant characteristics. Probably +1 to -1 range unless remarkable in case I'll maybe go with +2.
This has all been very useful - thank you very much!
Through the Aegis also has a bunch of pregenerated grogs.