I have a lot of fun participating in contests even if I can only make a few contacts in some. The hardest part about contesting is knowing what contests are coming up and finding the time to set aside to participate. Below are the top places I look for contest calendar information on the web. Always remember to check out the rules on the official site for each of the contests to understand the classes, exchange, times and other important rules that need to be followed, along with the log submission deadline.the bottom of this page.
The ARRL Contest site is a good resource for what is coming up this month and next. I really enjoy the ARRL Contest Newsletter which is sent out via email every other week and is available online as well.
Another site is the SM3CER Contest Service
There’s also the Contesting.com web site which is a landing page to many contest related links such as the CQ-Contest reflector where you can view the archives or subscribe to the mailing list and receive individual or digest (batched) versions of the posts.And underway is the Wiki Contest Compednium which might end up being another invaluable source for staying on top of what is going on and what is coming up.