Monetra is a scalable payment processing engine for Linux, Unix, and Windows. It is designed to handle credit, debit, gift, EBT, and check authorizations and is certified to support major clearing house protocols. Features include support for multiple modems, multiple merchant accounts, and multiple processors, all simultaneously -- as well as IP and SSL connectivity along side SQL database support. Designed in C, conforming to POSIX standards, and utilizing light weight processes (threads), this product is able to handle a large number of transactions with high speed and minimal CPU usage.
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.