General Removal Tools
Malwarebytes' Anti-Malware: http://www.majorgeeks.com/MBAM_d5756.html
A very good free malware scanner. It will find and remove most types of malware automatically.
Trend Micro HijackThis: http://free.antivirus.com/hijackthis/
HijackThis is a malware scanner and removal tool that can find and remove Browser Helper Objects, auto run processes, and malware services.
ComboFix: http://download.bleepingcomputer.com/sUBs/ComboFix.exe
ComboFix is a malware scanner and removal tool that can remove most types of malware.
Rootkit Removal Tools
Sophos Anti-Rootkit: http://www.sophos.com/products/free-tools/sophos-anti-rootkit.html
Sophos Anti-Rootkit is a malware scanner and removal tool. It scans for hidden files, registry keys, and running processes that can indicate a rootkit.
Malware Scanners
GMER: http://gmer.net/download.php
GMER is a thorough malware scanner only. It assists in finding hidden rootkits.
RootRepeal: http://download.bleepingcomputer.com/rootrepeal/RootRepeal.exe
RootRepeal is another malware scanner and reporting tool.
Sysinternals RootkitRevealer: http://technet.microsoft.com/en-us/sysinternals/bb897445.aspx
Rootkit Revealer is a malware scanner that compares API results from user mode and kernel mode calls that may indicate a rootkit is hiding itself.
Specific Malware Removal Tools
Kaspersky TDSSKiller: http://support.kaspersky.com/viruses/solutions?qid=208280684
Assists in removal of TDSS related rootkits.
Trend Micro CWShredder: http://free.antivirus.com/cwshredder/
CWShredder is a malware scanner and removal tool specifically targeted at removing CoolWebSearch
GooRedFix: http://forums.majorgeeks.com/showthread.php?t=182559
GooRedFix is a maleware scanner that looks for browser redirection malware.