<fudd>Just be "veeeeeeeewwwyy veeeeeeeewwwyy caweful (hehehehehehe)"</fudd> when doing all that "seeking." A client of mine found a site that provided one of those channels, only to also encounter a rather nasty rootkit infection which, in turn, led to a bout with "Google Redirect Virurs."
A rootkit is a piece of malware that invades the OS kernel itself and hides therein. It then acquires "Super user / Admin" privileges so it can do whatever mayhem it wants (in my client's case, cause the "Google Redirect Virus" infection). GRV manifests itself by tainting your search results in all the major search engines (Google, Yahoo, Bing, etc.) and sending you to other places (ie. ad sites, spam sites, etc.)... Thankfully, this one didn't send my client to any "adult" sites. You can tell you've been infected with GRV by generating some search results and then hovering over some links before clicking on them. If the "preview URL" you see at bottom left doesn't mesh with the context of the result over which you are hovering (e.g. it points to a hard IP adress that is unrelated), it's a good bet you've been infected with GRV.
Furthermore, rootkits can also invade your Master Boot Record (MBR) and even the BIOS EEPROM. If it does, the only thing you can do is either restore the system from a "safe" full FDR backup (that's a "sector for sector" image copy of the whole physical disk), or re-install the OS from scratch. It is not enough just to run a OS repair" procedure. The whole disk must be restored, and the BIOS re flashed. Thankfully, we did have a safe full FDR backup and did not need to rebuild. Most rootkits are stealthy enough to hide from the average commercial grade anti-malware/spyware software. It takes specialized rootkit detection software to find them. Even then, it's very difficult to clean them. The disk must, usually, be completely restored from a FDR backup, or be completely rebuilt/re-installed from scratch and BIOS re flashed. Trust me... it pays to backup frequently!
Just sayin... like the late, great Phil Esterhaus.... "HEY...HEY........ let's be careful out there!'