It never ceases to amaze me the websites that people will come up with and it will become incredibly popular. One of the most recent I have come across is Found Magazine. This is a collection of notes and photos that people find on the street, in parks, etc and then submit online. The notes range from shopping lists to love notes to drug deals. The pictures are random photos that they have found in cameras, on the ground, etc. It's a good website to visit when you want to get sucked in and waste an hour, or two or three.
And another popular website, if you haven't heard of it already, is Post Secret. People submit confessions/secrets anonymously on postcards and a small number are chosen each week to be featured on the website. While it may be interesting to indulge such a curiousity, the downside is that some of these secrets aren't for the faint of heart. Some could receive a R rating.
There is a similar webpage on Live Journal. It is LJSecrets and it posts a lot more secrets, more frequently than Post Secret. Like Post though, some secrets are rated R. It is easy to spend a ton of time on these pages, so beware.