A whole lot of white, plus one dominant color (usually blue, green or dark grey) used for footer/header.

Layout uses light-grey-to-white gradients to make gentle borders between columns and even tabs.

Borders that don't use gradients are always 1px grey.

Large rectangular rounded buttons in dominant color (or green, orange) with white lettering.

Sans serif font everywhere.

Bunch of links that don't fit anywhere are moved to lower footer in small font.

Approximately 940px wide fixed main layout.

http://www.loopt.com/

https://indinero.com/

http://www.nozbe.com/

http://www.peerindex.net/

Does anyone know how/why this came about?