Free Lonely Planet San Francisco for iPhone/iPod Touch

Apple's iTunes Store has the Lonely Planet San Francisco City Guide for free.  Normally this guide costs $16, but Apple's developer conference is this week in San Francisco so you're in luck.  The guide is great for locals and visitors alike, and even though the interface isn't extremely usable yet (it takes some effort to find things), there are some nice features like the mapping application that plots all restaurants nearby.  It's a great alternative to lugging a big book around while traveling, and you'll even get free updates automatically.