Credit cards come with a huge variety of perks, and a lot of them are familiar to us -- airline miles, cash back on purchases, rental car insurance, and so on. However, there are some unconventional and highly valuable credit card perks that you may not have heard of.

Here are seven perks that could save you a bundle.

1. Extended warranties
Many credit cards will extend the manufacturer's warranty for purchases made with the card. For example, American Express will add a year to manufacturer warranties between one and five years in duration, and it will match a manufacturer's warranty that's shorter than a year. Other card issuers have similar warranty extensions, which can give you peace of mind when you buy an expensive item. There are some purchases that are often excluded, such as motor vehicles, perishable items, and buildings, so be sure to check your card's policy.

2. Return protection
Some credit cards will extend the time window in which you can return items you've purchased, even if the store or manufacturer won't take them back. There is generally a time limit (90 days seems to be common), a maximum dollar amount per transaction, and a list of excluded items, but this can be a valuable perk if you need it. Discover, for example, gives you 90 days to return items valued up to $500, so long as the retailer documents its refusal to give your money back.

3. Trip insurance
I mentioned a couple of the travel perks that credit cards often come with. In addition to these, many cards provide forms of travel protection, including:

  • Trip interruption/cancellation coverage
  • Lost luggage insurance
  • Travel accident insurance

As an example, the Citi Prestige card provides lost baggage protection of up to $3,000 per person, per trip; up to $5,000 per year in cancellation and interruption protection; and up to $500,000 in travel accident insurance, provided that you used your card to pay for the trip.

4. Purchase protection
Different card issuers have different names for this perk, but it covers the theft, breakage, and loss of items you purchase with the card. Similar exclusions to those of extended warranty protection apply, but if you buy a new camera and accidentally drop it out a window, then you'll be glad your card offers this.

5. Concierge services
This perk is more common with higher-end credit cards. Depending on your card, concierge services can arrange travel plans, entertainment, dinner reservations, and more. The level of service from credit card concierge services can vary dramatically depending on how exclusive your particular card is and how much of an annual fee you pay.

For mid- to high-level cards (annual fees from $100-$500) that offer this, the concierge service can be useful for things like rebooking travel plans and getting tickets to concerts and events. With high-level cards like the American Express Centurion (annual fee of $2,500), concierges have been known to handle some pretty outlandish requests, especially for those customers who spend the most on their cards.

6. Price protection
There are a bunch of credit cards that will refund the difference if you make a purchase on your card and then find a lower price elsewhere. For example, Citi calls this "Price Rewind," and it allows eligible customers to register the items they purchase. If Citi finds a lower price within 60 days, the customer can request a refund of the difference up to $300.

7. Airline fee reimbursement
This is a common perk among travel cards, particularly the higher-end (read: high-fee) cards. One good example is the Ritz-Carlton Rewards Card from Chase, which offers $300 per year in travel credit that can be used for incidental expenses such as baggage fees, seat upgrades, lounge access, and other charges.

You may have to pay for the best perks
The credit card business has become highly competitive in recent years, and this has led to these and other perks, as well as sign-up bonuses and rewards, that are more valuable than ever. But the biggest benefits come with big annual fees. For example, the Chase Ritz-Carlton card I just mentioned comes with a $395 annual fee -- that's $95 more than those travel credits I mentioned.

That said, high fees can be worth it if that particular card's perks and rewards are valuable to you, so when you're shopping around for a new card, be sure to compare the perks and the fees before making a decision.