What are you using to capture ideas on the go? Everything seems either too big or too hard to use.

* Phones are painful to type on, including iPhone.
* Post-its are ok (I would prefer something even a bit smaller), but I haven't found any decent pens that fit the pocket - they're just too big and they fall out. I've probably lost a dozen of them already. I even tried the "space pen", but it was rather bad.