Bubble City is the (part of) a novel by Aaron Swartz for NaNoWriMo (National Novel Writing Month) in November 2007.
Mibbit is an ajax client for IM networks (IRC and Yahoo). You can log on via the site. They pass on your IP to avoid spam / abuse / etc.
YSlow is an extension for Firebug which shows ways to speed up page loads. It's published by Yahoo as part of their developer network.
Your chosen charity is paid if you search the web with GoodSearch, it's powered by Yahoo.