Previously mentioned voice recording reminder service reQall has rolled out a BlackBerry version (there's already web and iPhone releases). While the software includes conventional text entry, the big selling point is the ability to record voice reminders, tasks or appointments. Those reminders can be emailed to you, both as a recording and as a transcription. The recognition and transcription definitely needs improvement -- the word 'Add' got rendered as 'Had' and failed to recognise an appointment; what I actually said in the screen grab was "Organise the posts for Lifehacker for the rest of the week"; and it later translated a feedback message saying "It's a shame that there's no Australian dial-in number" as "whether the shine that they no Australian doll in number". However, given my Aussie accent and customary high-speed garbling, it could have been worse.
Even when accurate, the transcription takes some time, and it'd be nice to have proper integration with the BlackBerry's own calendar and task list. But if you'd rather say it than type it while on the go, reQall may be worth a spin. reQall is free to download and sign up during its beta phase (don't use the record-to-call option unless you fancy paying for international phone calls).