One involves someone saying they will sell you an extended warranty for your car. I've comically accepted the calls before for entertainment value (and to understand the scam a bit). Honestly, if someone calls saying your warranty is just about to expire a lot of things should set off alarm bells. Some of my favorite responses: "This is great timing! The transmission just went out in my 1954 DeSoto! Can I buy coverage to get it fixed?" Better: "I have a 2000 Hudson Hornet... You can insure that? Awesome!" The scams are well documented and the primary offending company was recently shut down. Hopefully the people executing the scam are doing jail time now.
Another scam involves someone from "Cardholder services." I've had a few of these end recently rather abruptly -- before I could say the phrase "Please take me off your list." The more generic the call -- the more likely it's a scam. Cardholder services to what card? What interest rate range are they talking about. Do they even know who they are calling (let me answer there -- no, they're doing robo-calling through a range of telephone numbers hoping to hit a live body).
In all cases, reporting these things to the FTC is a good idea. Here's the web site:
You'll find a link on there to also register your phone number in the do not call database.
Do your civic duty -- if you get a call like this, report the idiots and help the FTC shut them down. And if you're not pressed for time, it doesn't hurt to waste a little bit of their time (the scammers) in the process.