The age of low-cost flying is officially over. Budget carrier Frontier Airlines has announced that it, too, will begin charging extra fees for in-flight amenities like coffee, soda, and carry-on bags, says Joshua Freed at the Associated Press.

The airline says it will charge $2 for coffee or soda, "although its announcement on Wednesday did say that passengers will get to keep the whole can," says Freed. Passengers who claim a carry-on in advance will only pay $25 for baggage, but $100 if they wait to pay at the gate. Those who buy tickets on the airline's website won't have to pay at all.

Of course, charging passengers extra for carry-on bags isn't the only way airlines have nickel-and-dimed customers. In recent years, airlines — blaming dwindling customers and soaring oil costs — have found other, sometimes nutty, ways to make up for their sagging revenue.

Special carry-ons
Take note of what you're traveling with, said Joe Brancatelli at Bizjournals. Some airlines have very specific fee menus depending on the item. United Airlines may charge you between $35 to $200 to travel with dry ice. If you're checking a pet kennel on American Airlines, expect to pay $175 — "except on flights to Brazil, where the fee is a more modest $150," says Brancatelli. If you're into kite- or wind-surfing, expect to pay $50 on JetBlue. And before merging with United, Continental Airlines charged $200 to check vaulting poles for the track-and-field set.

Watch your weight
It's not just the size of your luggage that airlines are mindful of. Samoa Air stirred controversy earlier this year, when it started charging passengers according to their weight. Fees range from $1 to $4 per kilo to shuttle travelers between Pacific islands "that have some of the highest obesity rates in the world," says Harold Maass at The Week.

Charges at the gate
Some airlines can gouge passengers before they even step foot on a plane. Virgin America, for instance, will charge flyers $20 for a mailed copy of their itineraries. Spirit charges $10 for boarding passes printed by an airport agent.

Everything but the kitchen sink — and maybe that, too
Ryanair, mockingly known as "the Walmart of the skies," might take the cake for ridiculous proposals to save money. The Irish carrier encourages flight attendants to lighten plane loads by losing weight; once considered installing coin-operated lavatories; and charges passengers for paying with credit cards, changing reservation details, and — although this one's no surprise — in-flight food.