http://distrowatch.com/

The DistroWatch web site was first published on 31 May 2001. The concept started as a very simple table comprising of 5 major distributions and the chart only compared a few features (price, version, release date) and a few package versions (Linux kernel, KDE, GNOME, XFree86, Apache). In trying to make it slightly more comprehensive and useful, more distributions, features and packages were added until the table reached a fairly reasonable state in terms of information provided. At that stage, the table was moved from a spreadsheet into an HTML document and it was shared with the Linux community worldwide.