I've used Bluetooth a lot over the years to send images, address book and calendar entries to other Blueooth devices. While the technology is mature and pretty much works accross devices from different vendors it's always a bit of a hassle to use, especially when transfering something to a device of another person. That usually involves asking the other person to switch-on Bluetooth and to make his device visible for some time. Most people don't know how that works which, in many cases, kills the use case of transfering something quickly rather than typing in the information to be shared. But recently I've done the same via NFC authentication and the user experience is much better!
On Android the feature is called "Android Beam". When NFC is enabled on both devices, sharing an image, a calendar entry or a contact is as easy as bringing up the entry to be shared on the screen and then holding the two devices close to each other. A tone will played and Android asks the user if he wants to share the image/calendar entry/contact, etc. Clicking on o.k. will initiate the transfer, which is then done via Bluetooth according to the Wikedia entry linked to above and also from the data transfer times I've experienced.
Speaking of transfer times: Android Beam works great for small amounts of data, i.e. everything including images. Transfering videos is a different matter, their size is usually much too big for Bluetooth speeds.