WordPress is one of the more popular content management systems out there. I use it on most, if not all, of the websites I build for myself and for clients. But I rarely, if ever, use a free theme anymore. It's just not worth the risk if you care at all about the pixels on your website.

There's an article on WPMU.org making the rounds entitled "Why You Should Never Search for Free WordPress Themes in Google or Anywhere Else" that walks through the reasons why you probably don't want to use some random theme.

The main issue is hidden and disguised links back to some spammer, virus, spyware type site that helps them build their rank in Google because the more sites that use their "free" theme, the more links they have back to their site, which in turn, tells Google to rank that site higher. (That's a simplified explanation of how it works.)

If you've ever heard of someone saying that "their website got hacked" and they are running WordPress, 99% of the time it's their own fault because:

• Their administrator password was 'password' or something equally easy to crack. (Don't get me started on the laziness of passwords these days. If you're using the same password for everything, you've apparently got money and time to burn so more power to you. Check out 1Password if you're interested in a solution.)
• They hadn't updated their install of WordPress in 8 months (or longer).
• They were using a "free" WordPress theme that came with code injected in it that eventually blew up their website.

Here's where I'd recommend getting a WordPress theme:

• The official WordPress theme directory. Doesn't guarantee you'll have a good looking theme, but at least it will be a clean/safe theme.  This theme directory is also built into every WordPress 3+ install so you don't have to know how to FTP/upload files anymore making it super easy to try out different themes on your website.
• WooThemes. Definitely one of the top theme designers on the web, IMHO. Affiliate link
• Themify is where I found the theme for SSKTN.com but they've got some other really nice themes as well. Affiliate link
• Smashing Magazine, a blog for web designers and developers, routinely features free WordPress themes they've had developed for their readers that are hit and miss.