Until I started working with a tour operator client a few years back, I had no idea what Travelzoo was. If you visit their website, this is what they say:
Travelzoo is a global media commerce company. With more than 28 million members in North America, Europe, and Asia Pacific and 25 offices worldwide, Travelzoo® publishes offers from more than 2,000 travel, entertainment and local companies. Travelzoo's deal experts review offers to find the best deals and confirm their true value. While it does cost companies money to have their deals listed on Travelzoo, no amount of money ensures that a deal will get listed.
As I began to work more closely to learn how the Travelzoo relationship worked (if this was such a great piece of business for this one client, perhaps it could work for my other clients), I found out offering a deal via Travelzoo was a really good moneymaker for my client. If you were selected as one of the "Travelzoo Top 20" for a particular week (the deals are published at around 11:30 a.m. EST on Wednesdays), you can pretty much guarantee you are going to sell A LOT of inventory. But there is a cost of entry — sometimes starting at about $20,000+ per tour which the company making the offer often has to pay upfront!
But what I really liked about Travelzoo is the fact that they vet the deals to make sure they are, in fact, deals. Travelzoo runs the numbers and if they don't see that you are really offering a better deal than you are offering on your website or that they can piece together themselves if they are looking at a vacation package which includes airfare, hotel, etc., they simply don't feature it. And that means they have done most of the legwork for you so you don't have to compare pricing.
If you are a traveler simply looking for a great deal to Ireland or Italy, or on a hotel in a particular destination and you aren't tied to any particular brand, you don't care if the tour or hotel is five-star all of the way, but you just want to be able to see the destination and do so affordably, I highly recommend checking out Travelzoo.