hi, i’m considering a nexus 7 for my birthday, but was a little annoyed about the limited storage.

Amazon are offering this:
Nexus 7 cable linky

which from the description seems to mean you can use a USB stick drive as expandable memory. Given that a 64gig memory stick is only £25, it seems a bit of a bargain way to upgrade the memory.

Anyone tried this at all?

Yes, done. You need to root it (see youtube for walkthroughs) and an OTG (On The Go) cable (like the one you linked to, but ebay has cheaper ones). Then the memory card will show up like any other drive – suggest getting a file manager app such as ‘astro’ to find it tho similar to windows explorer.

There is an app that reads external memory, this is so you don’t have to route it. https://play.google.com/store/apps/details?id=com.homeysoft.nexususb.importer