I'm an Oracle DBA and a flash drive user. I use the Oracle SQL*Plus instant client and Command Prompt Portable to take care of most things, but a nice Admin tool is what I've been looking for. I think I may have finally found the thing! Please check out TOra - the Toolkit for Oracle. The website is http://tora.sourceforge.net/.
The third line down from the top of the page says, "This software is licensed under the GPL." Just under that it says, "NOTE: TOra was originally written by Henrik Johnson, with enhancements and additions by the open source community, and is now solely developed as an Open Source project. Any references to trial licenses or purchasing licenses purely apply to windows binary builds w/ versions prior to 1.3.15. Newer builds than that are 100% GPL licensed and can be freely used for any purpose."
The earlier Windows versions prior to 1.3.15 refered to are because of a non-free Windows build tool called Qt.
This is what the Red Hat IT folks use because it is GPL (and because it is such a great tool).
The current version of TOra is 1.3.21. There is a very long list of features at the bottom of the page listed above. As far as registry entries? I don't know. My understanding is that it was built for UNIX/Linux and was ported to Windows, if that helps.
If I can be of any further assistance, let me know.