In an ideal world, every mobile device -- smartphones, tablets, and so on -- would have a microSD slot for adding more storage. Heck, in a truly ideal world, they'd have two slots.
Alas, far too many mobile companions offer no expansion at all. That's when you have to start looking to external solutions -- namely, a media hub with its own storage and apps to stream stuff to your device.
Like this one: For a limited time, and while supplies last, BuyDig has the Escort MediaFlair mobile Wi-Fi hub for $24.99, shipped. That's after applying coupon code DIGIT at checkout. List price: $99.95.
The MediaFlair is a little (3.3 x 2.3 x 0.5-inches) black box consisting primarily of an SD slot, a Wi-Fi radio, and a battery. It comes with an 8GB SD card to get you started, but you can use just about any capacity. (Anything larger than 32GB will need reformatting, FYI.) Just as an example, Newegg has a Kingston 32GB Class 10 SD card for $16.60.
From there you just need to link your Android or iOS device to the MediaFlair, then fire up the corresponding app (Android|iOS|Kindle). Now you should be able to stream whatever music, movies, or other media you loaded on the card. Heck, you could use it to disseminate documents to a study group.
That's because it can connect with multiple devices simultaneously (though Escort doesn't specify how many). And thanks to its Wi-Fi connectivity, it has a healthy 100-foot range. I'd say the only downside is battery life, which is rated at just four hours.
Still, that's enough to let you watch a couple of movies on your next flight, all while keeping your phone or tablet storage free for apps and other stuff. If you're routinely running out of space, this is an inexpensive, effective fix.
Bonus deal: Want to add Bluetooth capabilities to your home stereo? Of course you do! And here's how to do it for cheap: Today only, and while supplies last, Meh has the XtremeMac USB-BTH-11 Bluetooth Home Connect Audio Receiver for $3, plus $5 for shipping. Amazon's price: $14. iOS users, make sure to read the description (which is both amusing and informative), as you'll need iOS 8 for this to work. Android users, you're golden.