How could I forget!

http://maps.google.com/

Best maps and directions I've ever seen, and the Street View -- I love being able to see where I'm going before I get there.

No new sites to mention, but these are great!

Great information. I have booked marked many. I was not able to get into any page that has a "tinyurl" in it. Are there alternate urls?

Does anyone know of a site with a travel planner similar to that on weather underground that covers Europe?

www.hopstop.com for subway & bus
in NYC, Boston, Chicago, SF, NJ &
Washington, DC

I second Google maps. Within Google maps, you can get directions, see if there is traffic, get satellite and/or map view, street view and find businesses. You can also drag on your route "line" and alter your route. Also, people create their own mashups for their favorite things, e.g. taxi fare, best pizza in NYC mashup.

http://www.airfarewatchdog.com to find better plane ticket prices.

http://www.biddingfortravel to bid for hotels (not a fan of Priceline for plane tickets.)

Not a big fan of tripadvisor as the customer reviews are not accurate.

Fodors is not going to like this, but I like the other travel guides as well - http://www.roughguides.com and http://www.lonelyplanet.com

Ever since my travel agent highly recommended a company with a D- rating w/ BBB, I plan all of my own trips. I use fodors (of course!) trip advisor, hotels.com and mapquest quite faithfully. For foreign travel I have been using hostel world a lot too. Great site!

www.foodandwine.com

For foreign travel, especially if you are country-hopping - www.xe.com for currency exchange rates.

These are great. I will try to think of more and add later - no time right now.

Bookmarking this list - what a great compilation!! Thanks!

I always check tripadvisor.com before booking any hotels.