The Alamin GSM SMS Gateway is a group of daemons that allows you to send/receive SMS messages from any GSM device that supports AT+ commands (GSM modems or GSM mobile phones) or supported by Gnokii. A client program allows you to send messages from any IP client. An SMTP interface is provided to allow MTAs to send SMS directly to the GSM network. IMP (Incoming Message Processor) modules allows you to extend functionality to implement banking, network administration, bd querys, etc. from a GSM mobile phone.
mptc is a Perl script to help you work out whether you're on the cheapest mobile phone network/tariff for your phoning habits. You feed it an itemised phone bill and tariff pricing information, and it will tell you how much that bill would have cost on different tariffs. So far it only supports UK network pricing systems, but could easily be extended and applied in other countries.
PyGCID is a graphical CallerID application written in Python with the GTK toolkit. It uses an external program to fetch numbers from your CID hardware. It maintains a small database with the incoming calls, and has the ability to store a comment and a note on each call. It can also dial the numbers using an external program, and run a specific program for each number (for example, you can play different sounds for different numbers).