Instead of CDs, read-only and long-term storable USB-sticks bundled with MP3/OGG/FLAC/… downloads. Big enough to fit some design on it and read-only to be able to use a more robust chips which will usable after a few centuries or so in a dusty box. For those users who want additional, non-virtual, benefits from downloading MP3s (instead of buying a CD). So

Mobile or smart phone (don’t know atm how much computing power would be necessary, so go figure) application with GUI for gnupg i.e. web-of-trust client. Should exchange public-keys and pre-encrypted messages, possibly checking the signature of incoming messages. And not more, since manipulating your private key (i.e. signing other keys) requires your passphrase and therefore complete trust in your platform, your surroundings, possibly your network. Stealing your phone should not compromise your private key, because then you’re very much in trouble. Personally the main benefit of this would be easy exchange of keys off the net and possibly a check button to mark if you’ve seen some identification from the other person. I could also imagine (if you have a dedicated root? server) to have a service somewhere, which could be used to encrypt/decrypt/sign things for on a secure platform, provided a secure transport to your phone, i.e. TLS. In any case you should have an automatic memory wipe tool included.

Then extend this to a meshed and distributed tool for a reputation network. But I have to read about that a bit more before including it here.

Business cards with your normal email address and homepage, but add another unique identifier at the end i.e. http://example.com/;foo so you can additionally control some additional bits of information. For example I normally won’t post my phone number anywhere, but using this identifier like a personalised password I can control who can see it and possibly revoke the access after some time. Of course using a secure connection will also protect against sniffing attacks if you worry about them.

For fun include also a qr code on the back.

Blimp lights, like the ones in Dune, except that I don’t remember their name. So some incombustible gas to keep it levitating, some way to adjust the height by adding or removing weight and a lightweight and flexible cable to provide power. LEDs to keep energy consumption and heat generation down. Shouldn’t that be possible in 2011?

Client-side filtering proxy

ie. ad- and malware-blocking, user-side script, stylesheet insertion and text, html, xml manipulation (regexes, xpath).

Because then you don’t have to write different scripts for different browsers (in the case of pure filtering). Parsing the stuff ourselves and then forwarding it to the browser (who parses it again) isn’t particularly efficient, but I don’t see how you can circumvent that for proprietary browsers (such as Opera, which I’m primarily using atm).

Should be error-resilient against malformed input (html, xml) and user-specified rules, ie. xpath expressions.

Since imho none of the available proxies quite fit my needs (yet one could possibly chain them, ie. one for ad-filtering, which is available, and the custom stuff ourselves, but I’d rather compile that stuff done into one single binary) there’s the question: When do I do this?

At the moment I have an Opera extension which does what I want, but for reason above this should be extended, possibly with dsl support for rules and optional compilation into state machines for additional speed-up (but which might easily backfire, so benchmarks are in order).