OEM BMW SES module for sale:

84 41 6 913 352 CONTROL UNIT, VOICE INPUT SYSTEM (list price $743.82 !!)

Most US spec X5's (and X3's, E46 3-series, e38 7-series, e39 5-series, and Z4) from model year 2000 and up have a 26 PIN connector hanging off their phone harness. This unit plugs into that connector to give you Voice Recognition (technically it's speach recognition). Here's a good post overviewing the commands.

http://www.xoutpost.com/bmw-sav-items...?highlight=ses

I mostly use it to get the nav map back on the display without fumbling with the menu, or phoning my common numbers though my phone paired to the BTUM or recording a short verbal reminder on the "notepad".

$200 + shipping

Here's the owner's manual: http://www.e38.org/BMW-03_00-Voice-Control-en.pdf

Note: if you have the BMW Assist module with Voice Recognition (2005+ ??), this module will not work as you cannot have 2 modules w/ VR, even though this module has more commands than the Assist box.