Is there any way to know how much traffic a website (that you do not own) gets?

Alexa.com

Google has a trends feature. For example.

It doesn’t give you any solid numbers. But if you know the numbers for one site you could do a rough estimate. Alexa only tracks people that have their toolbar installed. It isn’t very accurate.

Whoa… It looks like google offers more data. You need to sign in to see it though.

https://www.google.com/adplanner/

Alexa.com & Compete.com are both great. Alexia if all you need is general traffic/volume info, Compete if you also would like to see some demographics.

Don’t forget Quantcast.com. If a site is Quantified (meaning they share their data with Quantcast), then it’s by far the best measure. Otherwise, Compete is okay. (Off by around 5x for Fluther, fyi).

amung.us

@BBQsomeCows the link you provided is to an on-page analytics provider. In other words to get any data from their service you need to place a piece of javascript code onto every page of your site, @delta77 is looking for traffic information on other peoples sites.