If the shiny, happy, fresh-scrubbed “Web 2.0 look” is starting to look a little clichéd to you, check out The Academics of Worn from Airbag Industries’ Greg Storey. Greg talks about ways to leverage the shapes, typefaces, and colors of the past, and he links to Cameron Moll’s popular series of tutorials, That Wicked Worn Look. Besides sharing tips & PSD source files, Cameron also links to additional discussions and a a wealth of examples.
For more, see also these:

• Keith Bowman offers a great set of distressing Photoshop brushes & retro color palettes. I used the brushes quite a bit in redesigning this blog.
• The Mr. Retro series of filters makes it easy to weather your images.
• FontShop features a tutorial on giving your type the beaten-up stamp look. (Going the other direction, they also feature info on those bloopy Web 2.0 fonts.)
• [Update: CreativePro.com has added a nice, fast tutorial on aging an image, courtesy of Layers Magazine.

PS–Hey, no matter what, design these days looks better than ye olde Web 1.0 logos, right?