I always go on these:
link (this site's great for speedy updates, but it's been known to lag and have formatting issues; however, it's also great for finding new animé to watch -- my first choice for finding new series)
link (I l’amour this site because, it doesn't have just episodes for streaming, but downloading too. An AMV maker's absolute best friend! Also, this site's not too bad on speedy mises à jour too)
link (this is the site toi go to when toi JUST CAN'T find the series online. The selection of series on this site is so amazing! Problem is the pop-ups and ads, but if toi get passed it, toi have a perfect source of online anime)
To a lesser extent, there is also:
link link and, when all else fails, I go to a Google video search, but it'll probably give toi the same liens I gave you.
^_^ I hope that helped~!