it didn't show the exact volume of the traffic the site has but only the rank of it http://www.alexa.com/siteinfo/articlecube.com
Most of it must be direct traffic. One of my article directories has an Alexa rank of 27793 and less than 600 pages indexed in Google. It gets over a 1000 visitors each day. It gets some traffic from Google and Yahoo, but most of the traffic (90%) is direct traffic (people visiting the site to submit their articles).
I'm not too surprised by the Alexa ranking given where the majority of traffic is presently coming from.
Alexa ranking can be easily manipulated, just install alexa bar and keep refreshing (tell your friends the same thing). You can easily break 50k number.
well... i think it depends too on the number of countries the users enter the respective site; more countries in the list, the less the score is, because we know there are users in countries that don't even use alexa toolbar and so on.