A very nice list of power tools by Scott Hanselman. Most of these are free.
I would add the following to the list (most of which have already been mentioned on my blog some where in the past):
DesktopOK – Save and restore the positions of desktop icons.
DontSleep – Don’t Sleep is a small portable program to prevent system shutdown, Standby, Hibernate, Turn Off and Restart.
MobaXterm – Like Putty/SecureCRT, but better. Allows you to run XWindows apps over a ssh connection.
Agent Ransack – Search utility that adds a context menu for searching and allows advanced searching features such as searching for a text string in a set of files.
DirSync Pro – DirSync Pro is a small, but powerful utility for file and folder synchronization. DirSync Pro can be used to synchronize the content of one or many folders recursively.
GreenShot – Greenshot is a light-weight screenshot software tool for Windows.
FF File Time – A program that allows you to easily modify the time stamps of any file on your computer. It features an easy to use GUI that offers the possibility to modify not only single but also multiple files or whole directories.
Google Chrome – My favorite web browser! Add addons from the Chrome store such as GMail, Google Voice, Adblock and IETabs.
Free Download Manager – Why buy GetRight when you can use this program for free? Helps with troublesome downloads that like to stall out in web browsers.
Secunia Personal Software Inspector (PSI) – Secunia PSI is a security scanner which identifies programs that are insecure and need updates. It even automates the updating of many of these programs, making it a lot easier to maintain a secure PC.
QEMU Manager – Lightweight Virtual Machine emulator. Also has versions that run from a USB flash device. Seems to only use its own internal DHCP server and won’t use an external network’s DHCP server.
Zip2Secure – “ZIP 2 Secure EXE” is a utility program that creates self-extracting EXE files for Windows. Self-extracting EXE files are executable programs (EXEs) that contain a ZIP file and the software necessary to unzip the contents. No other software is needed.
– Soli Deo Gloria