a few of these have been mentioned, and a few are even in the database (though the links are dead). but there is a lot of really good stuff in here, so i'm posting anyway.
most of these are under 50kb. DelLater is just 3kb! i ran a few of them, and they were all single .exe files that did not write to the registry. didn't check them all though...
Advanced Process Termination (APT)
Very few programs in the world are resistant to APT's process-killing arsenal. With approximately 20 different kernel & usermode process termination techniques including suspension and fatal crashing, if APT can't kill your target process nothing can!
Advanced Process Manipulation (APM)
Take control over a process from within. APM is a process/module manipulation utility with a twist - by injecting itself into target processes it literally becomes a part of them, effectively giving you full ownership & control from the inside - you can even load your own DLLs.
Boot Sector Explorer
Boot Sector Explorer allows you to both read AND write to the boot sectors and Master Boot Records (MBRs) of both logical and physical drives.
File & Folder Unlocker
This powerful tool allows you to search for, and unlock, files that are in use/open/locked, as well as show you which process(es) are doing the locking. Also supports network-opened files!
A popular lightweight registry monitor which guards several important registry locations, including many key autostart locations.
ASViewer allows you to instantly view over 50 different autostart locations to check (and have complete control over) which programs are starting automatically when Windows starts.
If you can't delete a file because it's in use or if you simply want to delete a file upon system reboot then DelLater is the tool for you! Assembly source code included.
The quickest and easiest way to check the status of your Internet connection, NetCheck automatically performs DNS and TCP tests for you at the click of a button.
CSView is our freeware lightweight CSV (Comma-Separated Values) file viewer. Includes seamless support for compressed XCSV files, and can even export to BMP and HTML formats.
The popular mIRC client is the target of the vast majority of IRC worms that target IRC clients. This fast, free and lightweight IRC worm scanner makes it easy to detect and remove mIRC infections.
The easiest way to verify the integrity of files, this is our implementation of the famous MD5 algorithm - designed with ease-of-use in mind! Supports both file and text hashing.