Keylogging's simplicity makes it quite popular among thieves as Phishing takes a lot of time and effort and even the programming is often trivial, which sometimes can be developed by a 12-year-old hacker.

Symantec, one of the top antivirus fighters, reports that about 50% of the malicious software it tracks will not damage computers but rather, collects personal information. In 2005, iDefense, a Verisign arm that consults on computer security to industry and government, counted over 6,000 different keylogger variants. Digital signatures have been developed to prevent those programs before they are installed, but new programs with unique signatures are readily available from malicious code download sites. In some instances, buyers can purchase programs' source code and create their own variants of keylogger.

It's interesting to note that Keyloggers have been around for years and are also sold as legitimate applications as monitoring tools for concerned parents or suspicious spouses.

The best way to avoid them is to be careful of unknown web links sent via unsolicited e-mails, which is a first-line of defense and also avoiding questionable downloads and keeping up to date with Windows patches and antivirus updates.