As you've no doubt heard, the iPhone 4S may have a battery problem. Even if it didn't, you'd be wise to keep a backup battery close at hand, as you just never know when you'll need emergency power. The compact, rechargeable Duracell Instant USB Charger promises up to 3 hours of extra runtime. Toss one in your glove box or travel bag and forget about it--until you need it, at which point you'll be mighty grateful it's there. Amazon sells the charger for about $20.

Surprising but true: Your iPhone's screen can play host to all kinds of nasty germs. In fact, research shows that the average touch screen harbors 18 times as many germs as a toilet handle. Ew! You can keep your screen a lot cleaner by applying the Fuse Antibacterial Screen Guard, which promises to ward off 99 percent of germs. It also eliminates fingerprints and significantly reduces glare. The $30 price tag may be a bit hard to swallow, but if it keeps you from getting sick even one day, it's well worth it.

Going for a run? Put an app like RunKeeper on your iPhone and a headset like the $99 Jabra Sport on your ears. Designed for athletes in motion, this Bluetooth-powered stereo headset connects wirelessly to your iPhone, which can ride along on your belt, an armband, or wherever. Sick of your playlist? Switch to FM radio mode with the push of a button. Need to make or take a call? The Sport offers a wind-shielded microphone and active noise cancellation.

Apple's bundled white earbuds may be famous, perhaps even infamous, but not everybody loves them. For one thing, 'buds can get quite uncomfortable after a while. Plus, they do little to isolate outside noise, meaning you often have to crank the volume to hear your tunes--and that can be bad for your hearing. CNET has a longstanding love affair with the Klipsch Image S4 In-Ear Headphones, which offer exceptional sound quality, great comfort, and handy extras like a storage case and cleaning tool. Read Jasmine France's full review of the Image S4 to learn more.

Speaker docks are great, but most of them are meant to stay in one place. The Jawbone Jambox is designed to go where you go. It's a portable, rechargeable Bluetooth speaker available in your choice of "fun" colors: black, blue, red, and gray. (My advice: go with black.) Though almost compact enough to fit in a pocket, the Jambox's diminutive size belies its big, balanced sound. It makes a great addition to a den, dorm room, bedroom, or hotel room. Plus, it doubles as a speakerphone. And when you pair it with the iPhone, you see a tiny battery gauge right on the latter's screen. Slick. The only troubling part is the Jambox's $199.99 list price. But if you shop around, you'll find it for less online.

Which would you rather have protecting your shiny new iPhone 4S: a boring black shell, an ugly rubber bumper, or a beautiful color photo of your family, your dog, or something else meaningful? Thought so. Uncommon turns any uploaded photo into an attractive, durable case for your iPhone. The service offers four designs for the iPhone 4 and 4S, most of them priced at $34.95. And this isn't just a photo pasted onto a case; it's embedded into the plastic, so it won't rip or peel. It's a great way to make your 4S stand out from the crowd.

Do you routinely prop your iPhone up so you can watch movies, read e-books, play photo slideshows, and the like? Then you need a case with a built-in stand. The Zero Chroma Teatro is my favorite iPhone case ever for precisely that reason: it can lock into any of 13 angles in both portrait and landscape positions. But its rubberized kickstand folds completely flat when not in use, leaving you with a sturdy, hard-plastic case that's just as thin as an ordinary one. It's pricey at $39.99, but you'll be hard-pressed to find a more practical option for protecting--and propping--your iPhone.