Check out GetListed.org, or at least their free tool that lets you check your "claimed" listing in major search engines.
It's far from perfect at this point, mostly because the site is busy talking in "lingo" and not in local business-speak. But if you already sort-of understand your way around the local online lingo, it's a nifty check-up of whether you have dotted your i's and crossed your t's.
What do I mean that the site talks lingo? I typed Dr. Abed, 95126 (my dentist) and it showed no listings, even though when I went to Google and typed Dr. Abed 95126, she came up top of the listings. I typed in Zanotto's, (a neighborhood market) at it showed that the name had not been "claimed" on Google, Yahoo, Live but that it had 72 "citations" on Google. There was a link to click through and claim it, but no discussion on what "claiming" the name meant.
EDIT: Got a really nice note from the GetListed folks, and they pointed out that Dr.Abed's ZIP was 95128 - they are SOOO correct, which is what I get for making assumptions - and that her office is listed when done correctly.
Why, oh why (she asked again and again) do the online folks think that local businesses have nothing better to do than learn search-engine speak.
Anyway, Miriam Ellis writes a nice entry on why GetListed is good and useful and even necessary - and says nice things about the founders.