That is where posts like this come in. You'll find that most development blogs will have a post of this nature, where the author lists some of the cheap or free productivity tools that they have found useful.
Here is my list.
Notepad++
www.notepad-plus-plus.orgIt's like notepad but better; tabs, tab persistence between sessions, find in all tabs, and that's just the tabs!! You can even define your own language syntax to create custom document highlighting (if you want).
Unlocker
http://filehippo.comResolve sharing violations by removing a troublesome lock that another process has on that file. For example: "Hmm, I can't delete this folder, and even though nothing and no-one should be using it." - Unlocker to the rescue, albeit a dangerous and crude one. If this sounds abhorrent, try investigating the issue using ProcessExplorer (mentioned later in this post).
F12
Okay so you'll have this one already, but non-web-devs often forget about it. Press F12 when you are using your web browser and you'll find a whole range of tools here for the web developer. From performance monitoring to browser emulation, JavaScript debugging and CSS editing. There are so many useful items in here that people often neglect.ORCA
https://msdn.microsoft.com/en-us/library/aa370557(v=vs.85).aspxProvides a GUI for Windows Installer packages. Not only does this tool highlight validation issues, it also allows you to edit and save the new package.
WILogUtl
https://msdn.microsoft.com/en-us/library/aa372811(v=vs.85).aspxThis tool will parse your Windows Installer log files to help you identify issues with the installation and suggest solutions. It beats the hell out of searching for 'Return Value 3'
Kaxaml
www.kaxaml.comA lightweight XAML WYSIWYG editor. Keep things simple.
7Zip
www.7-zip.orgCompresses to 7z, TAR, ZIP and more, Extracts from 7z, TAR, ZIPm RAR and many more. If you've never tried it, run a comparison between the compression ratio of 7z compared to ZIP, you'll be pleasantly surprised,
ReSharper
www.jetbrains.com/resharperThis is a great productivity tool. It'll be interesting to see how quickly the new .net compiler helps the Visual Studio community close the gap, but at the moment you'll want to be using this plugin.
DotNetPeek
www.jetbrains.com/decompiler/downloadDecompile dot Net assemblies to C#. Sometimes we all get a little bit nosey.
BareGrep
www.baremetalsoft.com/baregrepHistorically the Microsoft Windows search isn't very good, but this flexible tool will quickly search for files matching your search pattern.
BareTail
www.baremetalsoft.com/baretailAnother from BareMetal Software, this time a log file parser. This tool will show log entries in real time, highlighting different types of entries based on keywords.
ASoft - DotNetVersion
http://www.asoft.be/prod_netver.htmlAn easy way to find out what versions of .net are being used on a client machine. The beauty of this tool is that the clean interface means that any tom, dick or harry can use it and even download missing versions directly.
KDiff3
kdiff3.sourceforge.netAn easy to use file and folder differencing tool. Run a comparison against up to three directories for differences or missing artefacts. Drill into files to analyse the differences.
ProcessExplorer
https://technet.microsoft.com/en-gb/sysinternalsFind out about a process currently running on your system. Target processes with the cross-hair or search the running processes to find out the ID of your target process, and what resources they are using on you current system. If you didn't like the Unlocker utility, mentioned above, you may prefer this tool as a means for finding what process has a lock on your file.
PowerGUI
en.community.dell.com/techcenter/powergui/m/bits/20439049Create and manage powershell scripts
And if that list has whet your appetite; checkout Scott Hanselman's list, it's much better than this one :)
All items listed are downloaded and used at your own risk. I have not been involved in the creation or hosting of any of these utilities and cannot make any guarantees over there safety. Please review all terms and conditions on the named applications and licensing before installing.
