I found a website with search engine which lets you download all the most popular files for free. The website says 22,287,515 free files downloaded till now.
http://www.freepik.com/

This is so sad that.....
Isn't there any law or rules for such website??? 

with just a little bit of clicking around it just looks like they are a search engine for images.  The one image I found just redirected me to the free image on photoxpress.  There are also a lot of Shutterstock images on there, but those are 'sponsored images' which you just click through to Shutterstock and then have to purchase like regular.

if the site they link to is giving away images for free legally, like photoxpress or sxc.hu then everything is legit.  If it's linking to a illegal download site then that would be different.  Can you link an example of a questionable site?  Everything I've found so far is just a legit free vector or image site.

I found collections of my vectors images with hundreds of downloads. I am not sure if actual download is from this site. It just takes me to webpage where I see
only ip address - probably it is redirect. The download was possible without problem...

They even state this false license note: Free for commercial use. (!!!) 
This is the most scary part. Even if they function only as search engine and copy this information from other places.

This is extremely serious issue for me.

can you post a link?

Yeah, that ones does look sketchy. It takes you to a site where members upload photos (with no control) and they have this little text on the bottom

All the resources on this website are the website users upload!
All the resources are not allowed for commercial use, otherwise you will be responsible for liability!
If resources have violated your copyright, please through feedback to us so that we can delete a timely manner to protect you or your companys rights!
contact us

I'd write to youtoart.com.. here is a link to your image there
http://www.youtoart.com/html/Vector/Animal_Plant/11909.html

I guess it is more youtoart who has the biggest problem .. and freepik has a problem linking to them.  If they are reported to Google with a DMCA and they get taken out of the google search results that would seriously hurt their business.

oh no.. I found one of image which was viewed 12531 and times 1138 downloaded.
I mean 1138 times download  , if that were legally bought then I could have earned few $$

I was browsing through the site and found few of them are legit but many of them link to illegal network. I personally nowhere uploaded my work for free....
Also it seems to be very popular site too as the Alexa rank is 3,517 with around Daily Pageviews of 312766 and company itself is saying 22,302,253
free files downloaded.... strangee 

These are causing huge losses to the industry. And such search engines also should be banned for linking to illegal sites for free downloads.