Sure, we’ve seen many phones with dual SIM card slots. Most are for the Asian markets, but the iPhone 4 is not one of them. Well, USBFever has come up with a solution to that problem, with a new $30 case that can hold dual full size SIM cards on the back of your iPhone 4.

It holds the cards in place and runs an adapter to the iPhone 4′s micro SIM slot. You can then switch between the two SIMs from the iPhone’s settings menu, though you can’t use both SIMs simultaneously.

Well this phone sure has an odd form factor. The Lenovo P90W features an interesting hinge design that allows it to be flipped open in either portrait or landscape mode. We assume it comes in colors other than pink, but we aren’t sure.

This pink wonder is also a dual-SIM Phone, so you’ll be able to use two SIM cards when you need to. No mention of price yet, but some specs include a 3-inch 240 x 400 pixel display, 3.2-megapixel camera, microSD card expansion, Bluetooth, GSM and UMTS support, and a QWERTY keyboard.

Myself, I don’t get having two SIM cards on a single phone. Maybe you just want the convenience of having separate numbers for personal and business use without carrying two handsets. If it works for you, it’s all good I guess. Now we have a dual sim watch phone. That may be going a bit far.

The $130 Q8 watch phone has the ability to have 2 numbers simultaneously, with Bluetooth, a 2-megapixel camera, video and audio playback, and a microSD memory card slot. That 1.33″ touchscreen display is going to be a real pain though.

The Samsung B7722 comes packing some cool features along with dual-SIM capability. Some of those cool features include dual standby, a 3.2 inch display screen with touch-sensitivity, Wi-fi, Bluetooth 2.1, FM radio, a 5 megapixel camera with LED flash, microSD expansion up to 16GB, 200 MB internal memory and the TouchWiz UI.

The Samsung B7722 is a good one for social networking as well. It also has 3G. This one will cost you $510 and is not bad looking if you need a dual sim phone.

Samsung seems to have a thing for dual SIM handsets and their latest is the Samsung C3212 DuoS. It’s great for those who want to separate their work and personal life. This model will arrive in Russia first, retailing for about $196, then it will be released in the European Union.

It didn’t even have specs at press time, but we’re guessing it will be EDGE. And it will likely have a bunch of business-minded features with nothing to offer teens or tweens or in betweens.

We’ve seen our share of dual SIM phones in the past. They’re for the greedy. Those who think that one sim isn’t enough. They’re hogging up all the sims. Do they care? No. They just keep making more. Like this General Mobile DSTL1, which will be Android-powered and hitting the US and Turkish markets before July.

Some features include : 624MHz Marvell PX310A processor, 5-megapixel autofocus camera, 3″ WQVGA LCD resistive touchscreen display, and a microSD memory card slot. It will cost you $550 to $750, depending on where it is.

Meet Samsung’s dual SIM phone dubbed the B5702. This dual SIM phone supports quad-band connectivity. It also has some other specs worth a mention, including a 3 megapixel camera with video recording, FM, RDS, FM radio and a stylish slider.

The design is simple, but elegant. It also features two LEDs that let you know which SIM card is currently in use. The phone promises a great net experience with browsing supported using both SIM cards.

We don’t blame you for not recognizing the name. Emgeton Enzo sounds like some kind of foreign race car driver or something, but the Emgeton Enzo is a cell phone. The 3G handset is powered by a Qualcomm/Philips chipset and can run two SIM cards simultaneously and independently of each other.

Some specs include: 2.2″ TFT display at 240 x 320 resolution, Tri-band GSM/GPRS/EDGE connectivity (900/1800/1900MHz), HSDPA 2100 connectivity (only for the first SIM card), Bluetooth connectivity, MP3/video player, 2 megpapixel camera, VGA camera for video calls, 50MB internal memory, microSD memory card slot

General Mobile is showing off their latest Android handset called the DSTL1. The company is known for it’s dual-SIM handsets, so it’s no surprise that the DSTL1 can take two different SIM cards. It also sports a 3-inch touch screen, 5 megapixel camera, 4GB of storage, WiFi, and a 624MHz Marvell processor.

The picture above is a render, but it’s what they envision the final product looking like. The phone should be released in the third quarter of this year. An Android handset like this one with the dual-SIM feature definitely has us drooling.