I've recently acquired (thanks, Dave!) a SanDisk MobileMate USB card reader, a 5-in-1 card reader (SD/MMC/etc.) about the size of many USB "thumb" drives. As SanDisk says, it's "ideal for memory-enabled mobile phone users and photo travel needs".
I had a chance to use it with my digital camera and laptop while travelling in Europe, and it was a great solution for off-loading pics from the two SD cards we were using in our digital camera, but its value extends beyond that: A mobile USB card reader + memory card is a useful combination that fits several data storage and transport needs as well or better than a traditional USB thumb drive. I'm not saying you should throw out your thumb drive if you have one, but if you don't, a mobile USB card reader could obviate the need to get one.
Benefits of the mobile USB card reader + memory card combination
- Enables you to make better use of the storage you already have - You most likely already have to buy some kind of memory card(s) for your digital camera, mobile phone, PDA, or digital audio player. Why buy storage twice? Mobile USB card readers cost ~$25, and allow you to use your memory cards (essentially) just like thumb drives. So, for a small additional cost, you get to really "leverage your investment" by using the storage you already have for more than just the devices for which you bought it.
- You get more value and flexibility of use from your storage - Imagine you have a camera, phone, and digital audio player that can all use SD cards, and you buy a 1GB card for each. When needed, you can dedicate them all to a single device, such as when taking the camera on a long trip. The mobile card reader makes the storage useful for more than just the devices you bought it for; it becomes a more general resource. You can load up all 3 cards with vacation pictures and video and take them to share with a friend. With 7+ megapixel cameras that take video, and 1 & 2 GB storage cards, this is often the most efficient way to quickly share lots of pictures & videos.
- Enables instant photo sharing - If you're with a friend and each taking pictures with your own camera, you can transfer a copy from your camera's memory card to your friend's computer, and put a copy of your friend's pictures on your card. That's something a typical thumb drive can't do. We did this a few times on our trip, and it's a nice capability!
- Doubles as a desktop card reader - Until WiFi becomes more common on cameras, a card reader is a much nicer way to transfer pictures to a computer than connecting the camera via cable. (If nothing else, it saves your battery!) If I had known about the benefits of a mobile card reader, I wouldn't have bought the desktop version -- that's part of why I'm writing this. NOTE: This is not a good solution if your computer doesn't have front-mounted or easily accessible USB ports.
Benefits of USB thumb drives
As I said above, I'm not against thumb drives, nor arguing that they're not useful. Here are some advantages they have over the card & reader combination:
- More durable - You don't have to worry about removing your memory card from the device, and securing it. Memory cards seem pretty durable, but I wouldn't want one floating around unprotected in my backpack, something I would comfortably do with a thumb drive.
- More software features & functionality - Many thumb drives are bundled with software & capabilities such as encryption, authentication (some via fingerprint scanning), running programs, serving as boot disks, etc. These are often vendor-provided and sometimes vendor-specific, and you're almost certainly paying a bit extra for them, but they can be valuable features for mobile storage. (There are probably not many technical reasons similar features couldn't be included on memory cards, but I think it's unlikely to happen given the way thumb drives are marketed.)
- More storage - I don't think memory cards are commonly available with quite as much capacity as thumb drives. The gap doesn't seem to be widening, though (internally, they're probably very similar technology), and is most likely to shrink.
SanDisk has introduced SD cards that plug directly into USB ports, which are certainly worth considering. I'm not sure that's likely to be done with mini SD and other card formats (but who knows?), so the mobile USB card reader may still be a better choice. (Of course, if the price is close, why not buy direct-to-USB SD cards even if you have a card reader?)
I'm sure there are other great mobile USB card readers in addition to SanDisk's. I just happen to have a SanDisk reader and cards and I'm happy with them thus far, so I used them as an example. I'm writing to illustrate the concept, not endorse this product in particular.