They've been doing it for years, but somehow I didn't participate in "SKN" until Jan. 1, 2006. Straight key night is a kind of ham New Year's celebration sponsored by the ARRL. For 24 hours, beginning at midnight GMT (7 pm EST in the US), this event encourages everyone to work many stations using CW (Morse code) sent by "straight key".
A straight key traditionally is the simple up-and-down telegraph key, well known from the movies. Lately, the definition has been expanded to include mechanical, semiautomatic "bug" type keys like the Vibroplex. Both these keys have largely been replaced by electronic keyers controlled by a key "paddle". An electronic keyer is much easier to use, especially at higher speeds.
Anyway! Straight key night encourages old-fashioned Morse conversations, and it's a lot of fun in a low-key and noncompetitive way.
I had contacts with 12 hams in the course of SKN: KB5IEU, WA7SPY, W6IO, KD5CB, PS8HF, ZS6SIG, AB5VA, WA5ZNU, XE1ELA, W3TMZ, N5KEV, and K8AQM, with time out to host a small New Year's Eve party at our house -- and some sleep.
SKN is old-fashioned, but as I was filling out QSL cards, I came across Leigh WA5ZNU's blog of our contact -- that he had already posted. You can't escape the Web!