Pinterest’s growth over the past six months has been nothing short of astounding. We’ve noted this before, but some new data today from Hitwise confirms the trend. Last week, Pinterest attracted 11 million visits, up almost 40-fold from just six months ago. Pinterest is now one of the top 10 social networking sites Hitwise tracks.

These stats are estimates of visits, not visitors, so you’d have to divide by how many visits per visitor Pinterest gets in a week to get the number of people going to the site. Pinterest is daily habit for many people, which is why it’s pageviews are going through the roof. Hitwise doesn’t break out estimates for visitors, but comScore has Pinterest at 4.9 monthly uniques in November, up from 3.3 million in October.

The visually-pleasing pinboarding site encourages members to collect photos and links to products. It is a socially curated shopping catalog, and it is addictive. It is also viral because everyone follows their friends’ pinboards.

Visitors tend to be female (58 percent), between 25 and 44 years old (59 percent). A lot of the visitors are from California and Texas, but Pinterest has mainstream appeal distributed across the middle of the country, with strong activity coming from Alabama, Tennessee, and Utah.