ADVFN stands for Advanced Financial Network and they are one of the world's largest financial websites. They are mainly targeted towards UK traders, such as myself, but I understand they now have country-specific websites all over the world.
ADVFN's main focus is on providing traders and investors will all the tools and resources they could possibly need on a day-to-day basis. So for instance you get free stock quotes, live streaming prices and charts of stocks, indices, currencies and commodities, as well as breaking news and alerts. There are even free bulletin boards where you can chat about individual companies and exchange investing and trading tips and strategies with the other forum members.