This is highly relevant to my interests.A picture frame that displays wifi-packet-sniffed images.
The ingredients: I rescued a to-be-scrapped laptop from Free Geek Vancouver (a Pentium II-450mhz Dell, if I remember) to provide most of the guts.
It's running Debian, with most of the boot scripts neutered and a custom script dropped in to start X, run Driftnet, and hide the mouse.
WebCollage can use DriftNet as an image source, you may recall.
I think that salvaged laptops make lousy picture frames. They run hot, draw an unconscionable amount of power, their power supplies tend to be the first thing to go, and they contain moving parts. The more-awesome way to build this gizmo would be to port DriftNet to a jailbroken AppleTV, or to one of those wallwart-computer dinguses. See also Newstweek.
Give it another year or two, and all those unused tablets that are going to appear on ebay/craigslist will be ideal for this - I'd guess this guys software would run close to untouched on an Android device...
http://piik.co/
I'm watching those tablets too. To be clear, I take no credit for the sniffing wizardry -- driftnet does all the hard work.
Someone was suggesting first-gen nooks are already there. Small, wifi-having linux box for ~$100. The epaper display isn't good for all applications, but it'd be great for some.
Oh please put this up in DNA Pizza if you're offering wi-fi.
If you find a place doing this, either of these websites are helpful:
http://www.evilscheme.org/defcon/
http://goatsepeg.com/
Jamie, thanks for the link. Agreed, salvaged laptops are pretty imperfect, but when all you have is a hammer etc. etc. This was a hack of opportunity and if I was to put some money into it I'd do things differently.
@Big is bang on. I'm already watching the crappiest of the cut-rate tablets drop in price and have a number of hacks lined up for them -- some of which will probably make these devices useful for the first time...
Permit me to ramble, but a particularly interesting/dangerous device for wireless sniffing is the WL-HDD wireless storage box. It's little bigger than the 2.5" hard drive it contains, supports wireless and can be flashed with OpenWRT or whatever. Imagine plugging this into an out-of-the-way outlet in an airport and coming back later to pick it up with a week's worth of logged traffic. I'm sure there are people already doing this -- way too evil for my tastes.
I think your fears are unfounded. Although it’s certainly easy to do that sort of clandestine logging, the results are incredibly boring. Image classifiers are good enough to winnow out some of the good stuff from all the web decoration cruft, but you’d still have to pay someone to slog through vast amounts of lolcats, fatgirl angle shots in bathroom mirrors, and whatever other garbage constitutes the majority of the typical Interweb user’s diet. And what are you left with? The occasional picture of someone “of interest”? Why not go take the pictures yourself with a spy drone or a good old fashioned gumshoe?
Textual data is a bit more interesting, but probably only profitable for corporate espionage. Beyond that it’s a waste of time and government-scale espionage has better techniques and technology.
tl;dr: Logs of public intertube usage obey Sturgeon’s Law.
Sorry, I was a little unclear -- I was mostly thinking about textual data, not just pictures, WRT logging to a hard disk. The big story IMO is credential sharing -- look at the recent HBGary hack and the Lulz Sony hack. Both used credentials from one service to break into another. An airport hotspot would be a good high-volume source of data including a lot of different people logging into a lot of unsecured websites. (And believe me, I have no interest in actually doing this -- it's just the kind of insecurity that the picture frame hack illustrates graphically.)
A friend of mine created a driftnet clone for rooted Android devices, and had me write most of the website documentation. http://piik.co
And even more previously...