Apple's iDevices famously -- make that infamously -- rely on fixed storage. If you need more space, well, too bad.

Or maybe not. There are a few tricks you can try, starting with this weird one that seems to magically free up some otherwise unavailable space -- anywhere from a few hundred megabytes to a few gigabytes. And if you're a Facebook user, deleting the app in favor of your mobile browser can net you 500-600MB. (Doing so improves battery life, too.)

But if you're seeking a really significant storage boost, your only option is to upgrade, right? You'll need an iPhone or iPad with more space.

Think outside the box

Not necessarily! External storage devices can give you virtually unlimited extra space for music, movies, photos, documents and other data. And many of them are surprisingly affordable.

These devices fall into two main categories: plug-in storage (think: flash drive for your iPhone or iPad) and wireless media hubs.

Plug-in storage

A phone-friendly flash drive will give you either a fixed amount of storage or a card reader that holds removable media (usually microSD).

For example, SanDisk's iXpand line offers anywhere from 32GB to 256GB, with a Lightning connector at one end and USB 3.0 at the other. It has a wraparound design so the bulk of the drive hugs the back of your phone or tablet, rather than sticking way out from the bottom.

The similarly designed Leef iAccess has no onboard storage; rather, it accommodates microSD cards, which could prove useful if you want to, say, view photos or videos captured on an external camera.

Drives like these aren't usually connected full-time; you access them on an as-needed basis. Suppose, for example, you're taking a long trip. You want to bring along your entire music library -- not just the handful of playlists that fit on your 16GB iPad Mini -- and enough movies to last you through two or more long flights.

With one of these drives, you can stock up on songs, podcasts, videos and whatnot, while still leaving space on your iDevice for apps and other stuff. You can even offload the photos and videos you've captured, thereby actually freeing up space.

In broad strokes, the plug-in drives work like this:

Step 1: Connect the drive to your PC, then fill it with any and all media/data you want to bring along.

Step 2: Install the companion app that goes with the drive.

Step 3: Run the app, then connect to the drive. Now you can stream your media, view your photos, access your documents, transfer files, and so on.

Go wireless

Don't want anything sticking out of your device. Consider a wireless drive, also known as a media hub. These come in many sizes and capacities, but make sure you choose one that includes a pass-through option, which allows your device to stay connected to a Wi-Fi network while simultaneously connected to the drive. Otherwise it's a huge hassle to disconnect and reconnect all the time.

What should you expect to pay for such a device? Probably less than you might think. The RAVPower FileHub Plus, for example, is a wireless media hub that supports both SD and USB media, and can connect to a broad range of devices (not just Apple stuff). It currently sells for $40 on Amazon.

That's a pretty cheap option for making extra storage available to your iPhone or iPad, especially considering this: the FileHub Plus is also a travel router and mobile charger. Its 6,000mAh battery powers not only the hub itself, but also any USB device that needs extra juice.

By the way, if you need a lot of added space, a few companies offer wireless hard drives that work much the same way.

Enlarge Image

For example, the Western Digital MyPassport Wireless comes in 1TB and 2TB flavors. It can back up your iPhone photos and lets you access music, videos and other media. Just beware that prices start at around $150, AU$200 or £130, and it's a bit too bulky to carry in a pocket.

If you want something a little more portable, check out the Seagate Wireless Mobile Storage drive, which features 10 hours of battery life and a pocket-friendly design. The 500MB model lists for $130, AU$172 or £107, but I've seen it for half that on Amazon. (Prices and availability are very much subject to change.)

In an ideal world, iDevices would have expansion slots. In this one, you can expand by way of external storage. Have you tried one of these products already? Tell us what's good, and what's not, in the comments.