Enjoy the following programs:

Find Any File (FAF)

For macOS. Shareware (try first, pay later). Now with High Sierra and APFS support!

Finds files by name, date, size etc. The perfect companion to Spotlight.

See the Find Any File page for more information and download.

Prefs Editor

For macOS. Free.

Edit preferences of any application. Like the 'defaults' command in Terminal.app, but easier to use.

See the Prefs Editor page for more information and download.

iBored

For macOS, Windows, Linux. Free.

The internet-enabled Block Oriented Editor is a tool to view and edit disk sectors and related files.

See the iBored page for more information and download.

More software I recommend:

iClip

For macOS.

iClip manages clippings of text, images and files. It optionally automatically records the contents of the clipboard every time you copy something. I am the main developer of iClip.

See the iClip site for more information and download.

Apps