One of the guys on my PreparedHam forum(see the link to the forum above in the Black Header bar) posted a link to a page that shows little known Easter Eggs on the Yeasu 857D radio.

I have had this radio for well over 5 years and never knew these things.

Example of whats there:
The Yaesu FT-857 has a number of undocumented features, some of which are very interesting. In no particular order, here are my favorite quirks.

XX Holding FAST for one second on the supplied microphone will toggle power.

XX The small wire on the power supply connector simulates the FT-897s internal battery sense line. When this wire is grounded, the FT-857 operation changes subtly.

With the display backlight in AUTO 2 (the default) and the sense wire grounded, the display light extinguishes after about three seconds, identically to AUTO 1 mode.

Also, the supply current drawn by the rig when it is turned OFF drops from about 8mA to about 2.5mA.

See more here:
http://members.cruzio.com/~k6xx/radio/quirk857.pdf