Travel Discount Guide

1. Aggregate Sites: Looks through multiple sites to find the best deals on restaurants, spas, entertainments, etc.
yipit.com.
Dealery.com

2. Your city or your destination city for discounts on restaurants, spas, etc:
giltcity.com
tippr.com
groupon.com
livingsocial.com
dealmap.com
Restaurant.com (Tip: google "promotional discount code for restaurant.com" and can get up to 80% off)

3. Destinations, flights, hotels, car rentals, etc:
bookingbuddy.com
travelzoo.com
* www.vayama.com
skyscanner.com ( Advice: A great site to look-up flight bargains within European cities. If you know German or other non-English European language, switch over to the appropriate setting. More options and discounts are available which are not featured in the English setting)
studentuniverse.com: Great deals on international travels for students.
* Check airlines' websites for special or promotional deals. For example: Koreanair.com is offering from LA, California to San Paulo, Brazil for $993.00
eurocheapo.com: Reviews on cheap hotels in Europe.
Bluejetcheeps: Sign up for their twitter. Announces specials on Tuesdays.
Farecompare: Sign up for their twitter. It offers location-specific fare sales when you plug in your home airport’s three-letter code, as in flyfromNYC.
Getaroom: Unlike other discounters like priceline.com, they tell the customers the name of the hotel and price before booking. But it offers an even lower rate through its call center — 10 to 25% off — to travelers willing to pay for the room before finding out just how much of a discount they’re getting.
Tablethotels: Luxury and boutique hotels
www.jetsetter.com: Offers limited time “sales” on really high-end destinations like at resorts, spas, villas, tennis camps, surf camps, etc. Must sign up and then every week, you'll receive an email on which destination is on sale
www.germanwings.com:  Discounted prices on flights, hotels, etc within Europe.
* kayak.com: Discounted prices on flights, hotels, and vacations.
* http://www.airasia.com/ot/en/home.page?cid=1#   Discounted flights throughout Asia

4. Vila rental: Often a better deal than lodging in a hotel. A great way to split the cost and save when traveling with a group of people.
homeaway.com
Zonder.com
Rentalo
rentvillas (Europe)
Wimco (Caribbean)
http://telegraph.perfectgetaways.co.uk/: Book directly with the owner without the commission fee

5. Home-stays:
Airbnb: For a 6-12% booking fee, it connects budget travelers with locals who are offering a place to lodge.
Couchsurfing

6. Tour guides:
Viator
* Responsibletravel - This agency does not sell discounted tours, but I find it very informative on enviromnental and eco conscious tours.
http://www.worldnomads.com - for travel insurance and safety travel inquiries. 7% discount on travel insurance: use the code " WNFANS". Unfortunately, this offer is not available to the US & Canadian residents.