Red: Fun Twist on the Defend-the-Base Genre 

Great find. Here are all the powerups I've come across. Let me know if you find others:

S = Shields. If you lose your shields you'll want to grab this powerup. With shields you can take 2 successive hits
P = Big shots. Your normal shots become those big "ping pong ball megashots for a temporary period of time
T = Extra turret. These are cool. A mini turret is plunked down next to you. You cannot control it nor is it very "smart" with respect to targetting, but it will put more ammo into the sky which is good.

Thanks for the tips, they help a lot!

324 seconds is all I've been able to manage so far...

I finally got around to trying this one. At first I was frustrated, because it took me a long time to realize that I had to click "Download" to actually PLAY the game (don't worry, it's not a conventional download - it loads into memory as a shockwave app).

The game is fun and intuitive. 423 seconds for me. Eventually what wiped me out was having too many turrets at once and trying to protect them more than the main cannon.

My favorite thing is to get the balls to stop in mid air. Doing that, you can juggle quite a few, keeping them all in the air at once. Eventually the wind or your turrets blow them away, though.