Astrology Junction is a site run by Jenna Sharron, who is an astrologer with 20 years experience. The site has lots of great information, particularly if you're interested in gleaning an overview in a variety of topics from the styles of astrology to the signs. Check her out here.
Astro.com is a site that will allow you to get all sorts of information. I use it to prepare charts, as they have an excellent extended chart selection--all for free! A word of warning though--the options beyond the defaults can be confusing, so be sure to know why you're choosing one option over the other before you do! Also, astro.com has an extended ephemeris selection (these are tables showing when planets are in which signs). So if you're interested in your transits, it's a great place to start!