One hundred dollars for a carry-on bag. No more free snacks. Having to pay to pick a seat?! With added fees everywhere, airlines certainly have found a way to rebound from their economic slump. Unfortunately for consumers, that means the “additional” fees associated with airline travel are through the roof, and flying anywhere can feel like a huge rip-off.

Of course, this trend was born out of financial desperation. The airline industry suffered across-the-board revenue drops following September 11, and was hit hard by the recession. And when corporate Goliaths experience desperate times, consumers can expect to bear the brunt of their desperate measures.

Today, airline revenue is soaring. According to a new study by IdeaWorks, airlines raked in a whopping $38 billion in what they call “ancillary” revenues last year. That’s an over $6 billion increase from the year prior.

"Airlines have boosted revenue by charging new fees as well as introducing ancillary products," said Jonathan Kletzel, U.S. transportation and logistics leader at PricewaterhouseCoopers (PwC), in a recent press release. And since the nickel-and-diming has paid off (to the tune of billions of dollars) don’t expect it to stop anytime soon. “Going forward,” according to Kletzel, "you can expect airlines to roll out additional sources of revenue, by strategically charging fees and bundling services that are aimed at enhancing the travel experience."

Here’s a look at some of the ways airlines are already ripping people off:

1. Something’s going on with the seats

If you’ve ever heard the phrase, “Sorry ma’am, you’ve been bumped,” then you know that you don’t always get what you pay for.

Overbooking is the practice of accepting more reservations than seats available on the plane. Airlines do this to compensate for expected no-shows, in order to make flights as full as possible. According to the Independent, this practice is a way for airlines to guarantee maximum revenue at the customer’s expense. Not only does the practice seem generally slimy, it can leave travelers stranded and split up families traveling together.

Britain’s biggest budget airline, EasyJet, was accused of doing this—and ripping customers off in the process—back in July.

But overbooking isn’t the only problem with seating. Also in July, the Associated Press reported that some of the major player airlines may be engaging in illegal collusion in order to limit available seats, which actually helps keep airfares high. Emily Pierce, a spokeswoman for the Dept. of Justice, stated that the department is looking into potential "unlawful coordination" among some airlines. According the AP, it’s possible that airlines illegally signaled to each other how quickly they would add new flights, routes, and extra seats.

Last but not least is the cost of seat selection. While more often than not, a seat assignment used to be included in the cost of a plane ticket, that is no longer true in every case. Many airlines today charge customers simply for pre-selecting their seats. And when there is no charge for reserving a regular seat, it’s almost guaranteed that there will be a premium seating option offered—for a price, of course.

2. An a-la-carte approach to pricing

Remember the good old days, when any little extra you might need while flying was free? By “little extra” I mean a snack or pair of headphones for watching the in-flight movie. More and more airlines are charging for things like in-flight snacks, headphones, pillows, and even blankets. Spirit is notoriously bad—they even charge for in-flight drinks. However, most other airlines still offer water and soft drinks for free. The same is certainly not true for food, however.

3. Bag it up

Carry-on fees, overweight bag fees, and checked luggage fees all exist. Be careful of baggage fees incurred at the gate. If flying an airline with bag fees, make sure and pay before you arrive at the airport—fees are typically lower online when paid in advance. And whatever you do, don’t show up at a Spirit gate with a piece of carry-on luggage that you haven’t previously paid for—unless you want to pay $100.

4. Fees, on fees, on fees

Other "ancillary" fees regularly charged by airlines include non-­Internet booking fees, unaccompanied-minor fees, pet fees, ticket change fees, and Wi-Fi fees. When you take additional fees into consideration, you realize that the lowest ticket price might not guarantee you the best deal.