Three useful blogs (and a wiki) regarding personal finance and investing:
Mr. Money Moustache: The one stop blog. An early retiree software engineer relates how he did it. Advises integrating saving and investing with a more frugal lifestyle to retire much earlier. It also has a forum!
Econowiser: Mr. MM covers everything, but being based on the US is not that useful for Europeans looking for specific advice ('this broker, that stock!'). This wise Dutch lady saves the day with her advice for European investors! She is a known fan of Dominions.
jlcollinsnh: Haven't actually read it that much, but has plenty of useful specific advice and resources (e.g. calculators). If in the US, it might be worth checking for picking the most appropriate index funds.
The bogleheads wiki: For a more structured approach or those who are sceptical about index investing.