WM Experts has a nice comparison video of the different Bluetooth keyboards on the market. WM Experts looked at the iGo Ultra Slim Bluetooth keyboard, the classic Stowaway, and Freedom Input’s Freedom Universal keyboard.
It looks like WM Experts picked the iGo Ultra Slim as the best keyboard on the market today, followed closely by the Freedom Universal. The Freedom Universal has the HID and SPP profiles to connect to both BlackBerry and Windows Mobile devices. The latest iGo Ultra Slim model is the smallest of the pack, although it does lack a dedicated number row. The Ultra Slim also is sturdy when opened.