Let's face it: the earbuds that came with your iPod, MP3 player, smartphone, or whatever probably bite. For my money, nothing beats the sound you get from in-ear earphones, which have the added benefit of reducing outside noise.
World Wide Stereo (via Buy.com) has the Klipsch Image S2m in-ear headset with microphone for $24.49 shipped. Retail price on these babies: $59.99 (though they typically sell for $30-40 elsewhere).
The Image S2m features an inline microphone with call button, making it a good match for your smartphone. (You can make/take calls without having to remove the earphones.)
It comes with three sets of oval ear tips, each a different size to best fit your ears, and a cloth carrying case.
The dozen or so user reviews on Buy.com average out to 4.5 stars, while CNET gave the Image S2m 3.5 stars, dinging it primarily for its "thin, tangle-prone cable." (Alas, most earphones are tangle-prone, which is why I've long been partial to this fast and easy method of cord wrapping.)
Ultimately, if you're not satisfied with the sound coming out of your stock earbuds, or you just want something that's better at isolating outside noise, these will do the trick. Klipsch has a stellar reputation in the world of audio, and $25 is a very reasonable price to pay for this kind of gear.
Bonus deal: Today's Giveaway of the Day giveaway is a good one: Paragon Drive Copy 10 Personal SE (Win). It's great for creating an exact clone of your hard drive (one of my preferred backup methods).