HEX3's JaJa is one of the first pressure-sensitive styluses on the market, and it is also the most unique. Instead of using low-power Bluetooth 4 to talk to your iPad, it uses high-frequency sound. This not only lets it work with the iPad 1 (or any capacitive-screened device whether iOS or Android), but means that the battery lasts for weeks.
I have been testing one out for a month or so now, and some big apps have now added support. So how does it do?