Windows Tweaker is a portable open-source tool which gives easy access to more than 100 Windows tweaks.
The program is a compact sub-1MB download, and entirely free of adware or other annoyances. Just download, unzip and it's ready to run immediately.
Windows Tweaker has a surprisingly sparse interface. While most tweaking tools try to impress you by displaying just as many options on one screen as they can, here everything is spread across 11 categories and 50+ subcategories. This does mean it looks very clean and uncluttered, though, and a search tool means it's easy enough to find tweaks: just type a keyword - "desktop", say - and any related options are listed.
The tweaks themselves aren't always as impressive. There's a lot here that are already accessible from Windows, if you know where to look (folder display options, default power button action, Windows update settings), while others are based around very familiar Windows tips (God Mode folder).
We also suspect there are a few bogus tips which do precisely nothing at all, including "unload unused DLLs after an application is closed". These won't do any harm, either, but they don't give you much confidence in the expertise of the author.
Despite that, there are also many useful tools. Would you like to limit the harm a non-technical user can do to their system, for instance? The "Restrictions" menu can disable the Registry Editor, Task Manager, Control Panel, even the right-click option in Explorer.
A "Right-Click" menu can extend your file/ folder context menus with options like "Copy to...", "Move to...", "Encrypt", "Decrypt", "Open with Notepad", and more.
There are several other tweaks which normally require Registry access. You can have your system show a message before a user logs on, for example. There's an option to set the number of icons displayed when Alt+Tabbing. Interface tweaks include adding Recycle Bin to My Computer, and including Registry Editor in Control Panel.
Version 5.2 changes:
?Redesigned the interface, to provide better contrasts
?Added new tweak to Disable all Windows+X hotkeys under Restrictions->Explorer
?Added new tweak to Disable password reveal in Windows 8 under Restrictions->Explorer
Windows Tweaker doesn't have any particularly surprising tweaks, but there are some useful options here. Just having 100+ settings available from one interface could save you some time, and the program's Search tool means they're reasonably easy to find.