I was thinking about getting a Kingston wi-drive or an Airstash when it occurred to me that these devices consist (principally) of memory and a wifi adapter, both things that my old ZTE Blade with its 32gb micro sd has (I'm sure most of you will have a similarly defunct old Android in a drawer somewhere).
I got to thinking, "Why not just charge up the Blade and use it as a wifi storage device?"
It is a simple enough matter to shift data using something like ftp transfer or dropbox over a wifi network or a cell network, but what about those times when you don't have access to a network of either kind (Google's cloud storage idea doesn't hold up well for these cases that come up really frequently in my experience). What is needed is a way to shift data from Blade (and it's SD card) to the Nexus 4 directly without any intermediary, just as you would from a mounted sd card.
So I looked into and figured that Wifi-direct would be the most appropriate way of transferring the data, but of course the Blade can't do this (Wifi direct runs only on ICS and JB, and it seems only on a few devices running these) .
So I looked some more... And I found a really cool app - "Fast File Transfer" - it's available free on the Play Store (I subsequently found a page on XDA developers about it - go there and have a read) and works with older versions of Android
In a nutshell it works by tethering your receiving phone to the sender, then it gives you a url (or a QR code, making things a bit easier) which you access with the recipient phone, then your file downloads really quick!
It needs no external network.
I tried it last night and shifted a 900mb file in about 6 minutes (probably the same amount of time as putting it on a usb stick and transferring it over). I then blutoothed the same file - it took 1 hour 40!
Note, I struggled to get this to work with the first Blade Rom I tried (a CM9 version), so I used JVentura's super stable EcoCM7 and it's worked a charm. Also the initial set up of Fast File Transfer - establishing the wifi tethering the first time - took a couple of goes, but once the link is stored you can re-establish it very easily for further transfers
Maybe others have come up with this or similar solutions already, but I'm really happy with this one, most significantly because it does not require any external network (but also the ease and speed involved rock!) It means now I can shove music, films etc on the Blade and go off to parts unknown safe in the knowledge that I'll be able to get at them with the N4. I reckon it should even work with huge games - I've not tried this, but I reckon if I use Titanium or similar to back up a game with it's data, it should be possible to transfer the backup file over to the blade when I need the storage on the Nexus 4, then switch it back when I need it again and restore it with Titanium.
Please let me know how you get on with this and if you've any ways of making the process more smooth (I'm trying to work out if AutomateIt or Tasker can automatically handle the tethering permission bit - you'll see what I mean when you try it out).