Links to some excellent websites related to Astronomy.

General Astronomy and Observing Information

Cloudy Nights

If you're interested in astronomy and you go to no other site, go to this one!  Absolutely the best place on the web to get help with your gear, your observing techniqeus, astrophotography, you name it.  The forums here are loaded with friendly, helpful, knowledgable people that are eager to share their knowledge and tips with anyone.  When the skies are clear, get out there and enjoy the night sky!  But on cloudy nights, go to Cloudy Nights!

SpaceWeather

Since the sun is the source of most "space weather", this site leans towards solar information.  It has images of the current sunspots and the solar disk in various wavelengths, tracsk solar flares and CMEs, and provides predictions for the auroras.  But it also has great user-submitted images, data about near-earth astroids and comets, and other itneresting astronomy tidbits.  Changes daily and well worth taking a look.

Tonight's Sky

One of the first questions stargazers ask is, "What can I see up there tonight?"  This site answers that question simply and easily.  Enter information about your location and what kind of gear you'll be observing with such as binoculars, small telescope, large telescope, or even naked eye viewing.  It will provide you with a list of interesting objects to look for and what times they can be seen.  Great for beginners or advanced observers alike.

CalSky

Similar to "Tonight's Sky" this site determines what will be visible in the sky on any given night.  It's a bit more advanced and takes some more setup, but will also reward you with astronomy-specific weather forecasts, predictions for meteor showers and eclipses, and other astro-information such as details about the planets and their moons.  If you only observe occasionally and don't want to constantly check these sites, CalSky can be set up to email you when the weather is conducive to observing, or when special events such as eclipses are occuring.

Online Retailers of Astronomy Gear

Most areas of the country no longer offer a convenient local store to go to for astronomy gear.  Most purchasing is now done online, and there are many, many quality retailers available.  These are just a few of my favorites in the United States.  I won't list the big manufacturers such as Celestron or Meade since they obviously have their own well known web sites.

Astronomics

Located in Norman, Oklahoma, this retailer has the laudable distinction of being the owner and benefactor of the Cloudy Nights website (see link above).  If providing this extraordinary resource free of charge is not enough, they also give a small discount to Cloudy Nights members.  In addition, they are the parent company of Asto-Tech, makers of some of the finer telescopes and accessories available.  They are a quality organization with top notch customer support and definitely worthy of your business.

Agena Astro

Another excellent online retailer which offers most of their gear with free shipping.  When you shop around, you'll find that they are consistently a little less expensive than their competition.  Customer support here is also top shelf.

ScopeStuff

An ecclectic site with all manner of accessories both mainstream and oddball.  When you need that strange little bit or piece that no one else seems to carry, try here.  Their prices sometimes seem a bit higher than others, but be aware that they include shipping in their prices so they don't charge extra for it.  For most other sites, when you add in shipping, their prices are similar to or higher than ScopeStuff.

ADM Accessories

This is a machinist that specializes in making top quality hardware for telescopes and mounts.  Items are not cheap, but reasonably priced given the high level of machining precision and attention to detail.  This is the go-to place when you need the right pieces to put together a solid astrophotography rig.  Its worth stopping by this site just to see the gorgeous pieces of hardware he produces.

Orion Telescopes and Binoculars

Deserves a mention as one of the longest standing retailers of many brands of telescopes, mounts, and accessories.  They also carry their own brand of many items.  Loads of gear here, lots of innovative products, and just a great place to spend time astro-shopping!