Ninja Slash (fun flash Friday). Move left/right/up/down to kill zombies faster and faster.
RUN! is a single-button flash game. Hold A to run, and let it go to slow down. There are three difficulty settings and five levels. The music, design and sfx are off-putting. You will probably either hate it or play it for about 3 hours, and then hate it. [more inside]
Give ten grains of rice for each word you get right. It builds up very quickly.
Friday Flash Fun: Kongregate has a variety of games, including my current fave Castlewars, a card based game where you win by building up your own castle, or utterly destroying your opponent's castle. You may also enjoy luminara, which I can only describe as the dance version of Asteroids. Or, you could just have a monkey fire at balloons with darts.
Get Hostile! - Inspired by the well-beloved Avalon Hill board game Acquire, Get Hostile! is a free, web-based board game that has already sucked up hours of my time. Check out the quick tutorial to get up to speed, then play against live opponents or AI's, forming corporations, buying stock, and doing hostile takeovers!
The Veridian Room is Toshimitsu Takagi's long awaited sequel to The Crimson Room. Point and click puzzlers to destroy your brain. Just in time to eat away your whole Flash Friday. Mirror here. Via my mate Duncan, who got it from Albino Blacksheep.
Fiendish bouncing snake game. Requires Java and lots of spare time.
Soda Jerks Flash fun for a Friday afternoon. Couple of funny cartoons, the most recent a spoof of Joe Millionaire.