Here are a few sites that I love to refer to pre-, mid-, and post-travel: 

WikiTravel

Newly discovered on my part.  Although I'm a fan of the 5-inch thick travel book, this site provides solid ground basics for almost every country out there: Demographics, History, Culture, Main Cities, Pointers, and more!   

CouchSurfing

Pure genius.  This is a community site that allows its members to request to "surf" someone's couch (i.e. a couch/bed/floor to sleep on) almost anywhere in the world!  Of course, the experience usually turns out to be much more than having somewhere to stay for the night and I myself have couchsurfed a total of 8 times in Europe and Australia.  Although my very first experience was a little awry (feel free to e-mail me for details, if you're that curious), all of my hosts thereafter were some of the most genuine, kind-hearted people I've ever met.  Couchsurfing experiences will renew your faith in this world!

World Wide Opportunities on Organic Farms 

'WWOOFing' is an experience that I've heard many speak of, but have yet to try for myself.  WWOOF is a worldwide community that provides opportunities for people to volunteer on organic farms across the globe.  Generally, each country has their own organization, which may charge a small membership fee for arranging contact between volunteers and local farmers.  In exchange for your help, food and board are included, in addition to a guaranteed unforgettable, educational experience!

JobsAbroad

In fact, this is the site where I found the contact information of the Torino-based Au Pair agency in 2005.  You can search for any type of job in almost any part of the world and you will be provided with the details of numerous companies or organizations that are looking to hire.  When I'm not doing schoolwork, I can be found browsing this site and daydreaming about my next escape..

Everyone's favourte, Facebook 

Yes, although we all have this love-hate relationship with Facebook, I use this as a means to keep in touch with all the super people I've come across during my travels!  While I'm away, it's also a much more convenient way to post pictures to keep friends and family updated.  So aside from how extemely distracting it is, Facebook actually serves a purpose!