• Ryanair: (a British-based airline, most flights originate in the UK or Ireland)
• EasyJet
• GermanWings (Obviously, a German based airline. Most flights originate from Germany)
• BMI Baby
• VolaGratis: (an Italian website – also available in English – that gives you a comprehensive list of low-cost fares between the destinations that you specify)

As with most airlines, the earlier you book, the cheaper the fare. But generally, you can fly between major European cities for less than 100 euros round trip. If you happen to catch a fare sale, it can be far far less than that (I've seen fares for one British pound each way, excluding taxes). It's also worth noting that most of these airlines are no frills. They don't serve snacks or drinks for free, so bring your own. Seating is generally first come-first serve.

Resting Your Head While Saving Some Change

If you're not too picky about where you stay and basically just need a clean place to rest your head at night, you have some really inexpensive options. The Internet is a good resource to find inexpensive hotels. Just do an Internet search for hotels at your destination, and it will bring up a lot of sites that will allow you to compare prices and amenities. If you want a private bathroom, these sites will let you know if one is available in the room. Many of the sites also have pictures of the rooms and hotel amenities. You may have to give up some comforts, such as air conditioning—most hotels don't have it. But most do serve a substantial free breakfast. A typical European breakfast consists of assorted cold meats, cheeses, and breads, condiments, yogurt, perhaps some hard boiled eggs, coffee, tea, and juice.

If you don't mind staying in some soulless chain hotel, there are some inexpensive options there too. Etap and Ibis hotels are both part of the Accor Hotels family: —and are reasonably priced. A room at Etap can also sleep three comfortably (a double bed and a bunk). There are usually several to choose from within most major cities, so you can pick one according to the area of town in which you wish to stay (a map on their website pinpoints the location of the hotel). These hotels typically have air conditioning and private baths, but you have to pay for their breakfast and it's not very good. But it might be worth it to you to only have to pay around 50-60 euros per night (at Etap, Ibis is a little bit more) to stay in Paris or Amsterdam. You can always stop at a bakery for croissants and coffee.

Cheaper still are hostels, if you're a student backpacking through Europe or on a trip with friends. Generally, you have to give up some peace and quiet and a private bath, but you also have a better chance of meeting new people from all over the world. Just do a search for hostels online to find one that is right for you.

And just because you're traveling on a budget, that doesn't mean that you have to rule out a Bed & Breakfast or an apartment (for lengthier stays). The Internet is a great source for those too. Many B&B's in England are even cheaper than hotels, although you may not get as much privacy or your own bathroom. I found some pensions (short-term rental apartments) in Prague that had a living room and full kitchen for less than 100 euros a night! And with a full kitchen, you don't need to eat out for every meal.