Many times spy software is confused with spyware, but they are two totally different conception.
Spyware applications are typically bundled as a hidden component of freeware or shareware programs that can be downloaded from the Internet. Once installed, the spyware monitors user activity on the Internet and transmits that information in the background to someone else. Spyware can also gather information about e-mail addresses and even passwords and credit card numbers. This information is then sold to a third party.
But spy software never do such things. Keylogger, known as a spy software, is used to monitor or record all activities occurring on a users computer. This software is installed directly by the user wanting to perform the monitoring - rather than hiding it on top of another software installation. Now, more and more parents use keyloggers as a good parental control appliance helping them manage their children to use Internet appropriately. It's safe, useful , convenient and effective.
The following links would be helpful. They offer full reviews of spy software
Mac
Mac Spy Software
PC:
Remote Keyklogger
Phone:
Mobile SMS Spy
Nowadays. the soaring development of technology make our life more and more wonderful, computer becomes an indispensable part of everyone's' daily lives, then how to make the most appropriate use of it, we need the help of spy software.

BUT NOTE: Be sure the thing you install spy software belongs to you, or you will be landed in to court!