What a creepy remark "This is your third post about selling homes that sounds a awful lot like you have some more serious questions that you are not disclosing."
I like asking questions thoughtful questions, but so far I've never gotten a less helpful or more creepy response than yours. I'm signing off for good.

JT
This is your third post about selling homes that sounds a awful lot like you have some more serious questions that you are not disclosing.
Are open houses effective? Yes.
Neighors responsible for referrals? Yes.
Sources indicating showings? You know, I find your curiousity piquiing mine...
We call this "activity". Showing activity can be measured by:
Having Realtors and guests "sign in"
Collecting business cards at Broker opens
Keybox activity

Hope this is being of help to you.

JT -

Here in San Jose there are two ways to know how much a home is being shown. First and easiest way to get an idea is by how many cards are being left at the home by the agents showing. Not all leave cards but most do. The listing agent also has the ability to check the lock box and see how many have opened the door. This is still an estimate as many of us preview homes but never show it to a client.

But as far as an online way of knowing the activity, I don't think there is any. Asking the listing agent directly is allowed and might be the easiest way to go.

CJ

There are no sources, that I'm aware of, that would tell you how often a home is being shown (other, of course, than sitting across the street, watching the Mercedes, Jags & Lexus's come and go).

That would be private, and the only ones privy to that information would be the listing agent/agency and the seller. As you can imagine, that would be handy information, as a buyer, to have that would be helpful when planning an offer, which is precisely why that information is not available to the public, and the only answer you'll get from a listing agent when asked that question is "we're getting a lot of interest and activity".

Buying and Selling a home is a bit of a poker game, and the closer you hold your cards to your chest, the better.

I am not sure how to answer that for your area, however in San Diego we have Sandicor. Whenever a Realtor shows a property that information (the Realtor accessing the lock box) is sent to Sandicor than the listing agent can retrieve that information form the MLS. In your case you can ask your agent for a report to see who has seen your home.