According to them, " TaskList.org is the ultimate resource to help you determine if your computer is infected with spyware, adware or viruses."

Recommended and used by me.

As described on the site:

What it does ...
The Hosts file contains the mappings of IP addresses to host names. This file is loaded into memory (cache) at startup, then Windows checks the Hosts file before it queries any DNS servers, which enables it to override addresses in the DNS. This prevents access to the listed sites by redirecting any connection attempts back to the local machine. Another feature of the HOSTS file is its ability to block other applications from connecting to the Internet, providing the entry exists.

Overview (from the Michael Horowitz site)

Malicious software goes by many names: Spyware, worms, viruses, Trojans, Adware, keystroke loggers, pests, and more. "Spyware" often is used to mean all malicious software other than viruses. I use the term "malware" instead.

MLabs ... Scoping out the digital world.
Lists a number of products for monitoring, snooping, protecting individual computers or networks.

Several online tests for internet connection speed, spyware, and checking your computer for various problems and capabilities.

PestPatrol anti-spyware program. Their blurb:

Detects and Completely Removes:
Spyware and Adware that "phones home" information about you, your computer, and your surfing habits
Remote Access Trojans (RATs) that allow an attacker to remotely control your computer

Free windows process library with info on spyware, adwares, trojans, viruses, system processes and common applications.

Spybot is a 'must have' program and it's free. Here is the download link. Also recommended is Ad-Aware. See comment below. Should run both because some spyware will evade one but be caught by the other. Note: there is a potential situation where running the spyware removal can result in loss of your internet connection. See http://dajudge.us/dr/capnj/node/view/273 for the solution if this happens. If you have difficulty finding this on the site, the file you are looking for is WinsockFix.zip. It may be available from other sites as well.

Their intro:

Spyware - a Hidden Threat


Spyware programs are a growing threat to corporations today. Reports now show that nearly one in three computers are infected with a Trojan horse or system monitor planted by spyware.

Comprehensive review by pcMagazine of all products.

This is a page at PCworld that hopefully won't change soon. It first touts Ad-aware but then lists every other spyware resource that someone should consider.