The usual... sales, prices, inventory, days on market.

I watch them all Peter. Even the wrong ones....

More important to indicators is speaking with agents around the Country

I look at the local numbers for my area to see what the market is doing

Sales, new construction start ups, what are the small builders doing ( the ones that usually build 4-6 houses a year).

It is something i can usually see. The amount of new listings vs how quickly they are selling or not selling.  WHat are they selling for? I like to look at interest rates as increasing rates can lead to a spoke in sales followed by a slow down like we saw last fall. Then when rates came down in January, a big spike in sales which continues.

The excellent statistics provided by our mls software.

Nina Hollander nailed it. I also listen to those in the business.

I watch what the market is actually doing - how buyers are responding and how many sellers are feeling remorse for missing the "peak" of this last insane seller market. 

We have experts that monitor this every month and send us the reports, good to know where we are going and when.

I wish I knew.

Don't watch any...

DOM, activity at open house. Layoff notices....

Too many to name. However, one that is extremely overrated is days on market.

In agreement with Nina Hollander 

Like Nina Hollander said, the usual suspects.  Price & changes, DOM, inventory levels, sales.  I also look at the agent remarks from time to time to see if bonuses are being offered or if commissions are being raised.  That's a good sign of a slow market.

An interesting subjective question thank you. I know the car market slowing for 3 or more months signals Real Estate changes. Days on market for properties for sale another indicator. Interest rates, e-z loans and rents going up and staying there speak as well. With any profession practiced by a passionate professional...one can also "sense" something afoot....& take note

The typical - interest rates, price trends, inventory levels, DOM, average closed price to list price percentage. One not so common item I look at is the difference between the Average & Median Sold Prices and the Average and Median Asking prices -there's almost always a gap - but it's whether that gap is getting bigger or smaller - that I use as another indicator. However, there's not "one" it's looking at all of these things and their interaction that gives one an idea of where things could possibly be headed.

MLS information.

When I was active I checked the MLS thoroughly every day.

I watch all the data monthly stats, but also the unemployment, and job growth.

Weekly inventory going up or down.

Inman Headlines?

Seattle then Portland tend to be a leading indicator for my area.  We trail them by 6-12 months it seems.  I also track local activity on a month to month basis.