Recording a conversation on your smartphone isn't as easy as you think it would be due to varying and ambiguous laws. While the legalities might be hard to get around, you can still simplify call recording with the U2 Mobile Recorder.
In a roundabout way, the $US134 U2 Mobile Recorder simplifies the act of recording a call on your iPhone or Android device. You just plug it into the top-mounted headphone jack of any phone, except the iPhone 5, and hit record.
Four gigs of non-expandable storage should be able to hold up to 144 hours of conversations, and a USB port allows the recordings to be dumped off to your PC. It's also got its own headphone jack for immediately transcribing a conversation. On a single charge, it can record or play back for about 20 hours, which is perfect for even the most long-winded of snitches. [Amazon via 7Gadgets]