For 1/10 off-road and all on-road, it's RedRc. For 1/8 off-road it's NeoBuggy. They are the best English language sites out there.
There are a number of other good English sites like RCArea and oOple, and also good Japanese sites and a good German site too.
Don't forget the various magazines, almost all of which now operate news sites. R/C Car Action has a reporter and web-guy devoted almost entirely to reporting and posting web news.