X is for X marks the spot

X marks the spot - A place on a map where you put an X on the postion the hidden treasure is located.

Xanga - A blogging platform/community a bit like typepad.

Xat - A free, instant chat room maker/service, usually in a widget, mainly used by younger people but can be customized and used for any age range. Coffee Xat

Xing - A business social networking website, a European slant, similar to Linkedin.