N900 has both FM receiver and FM transmitter.

http://wiki.maemo.org/N900_FM_radio_transmitter
FM transmitter can send signal several meters. It's generally designed to send audio signal to nearby radio (for example, car radio) and uses the built-in antenna of N900.
The application FM boost maximises the transmitter power. In some cases, this may improve reception of the signals by a receiver (for instance, car radio). In others, the transmitter will already be set to highest output.

http://wiki.maemo.org/N900_FM_radio_receiver
The N900 FM receiver allows the reception of broadcast FM radio signals using the headset/headphones as an antenna.
The FM radio is part of the Bluetooth chip. It receives FM radio signals using the headset or earphones plugged into the 3.5 mm socket as an antenna (actually arbitrary headset/headphones, or any other cable, for this purpose).
There is an application to "turn N900 into FM radio", to give comfortable interface for listening to radio stations.
http://maemo.org/packages/view/fmradio/

I haven't used the application before, but I will test it soon.
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I rarely use Bluetooth but I have successfully sent JPEG photographs in both directions (to and from N900) and I have once sent an mp3 file from N900 through Bluetooth. The problem is, the second Bluetooth device is a cellular phone which could neither play an mp3 file after receiving it (the phone doesn't comprehend this file extension) nor send its own video files (special file extension) through Bluetooth.

So far, I haven't found any problems with N900. It takes wonderful photographs, catches GPS signal, reads barcodes (mbarcode), scans documents (FrontViewN900), allows me to log my walking (modRana). It can be used as a flash-light (http://maemo.org/packages/view/flashlight-applet/) or a remote control (http://maemo.org/packages/view/irreco-for-n900/).

Don't hesitate to ask questions. You are welcome.
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To know more about N900 capabilities, visit
http://wiki.maemo.org/Category:N900_Hardware

You can edit LED pattern (I have already done it; easy, but no mistypes permitted) or over-clock CPU (Don't even try! It's too dangerous!).
You can get another operating system (Ubuntu, Android, MeeGo). And multi-boot different operating systems.

Or you can leave hacking to others and use N900 in a normal way, enjoying the fact that it works without command-line.