After working with various sensors and not being happy with the speed of mathematical calculations, Arduino and AVR enthusiast Alan Burlison has described and demonstrated the use of fixed-point arithmetic with Arduino. This method can speed up calculation times and is necessary as the AVR microcontrollers used in the Arduino don't have floating-point support. Alan demonstrates various functions and in doing so illustrates the strengths and weaknesses of the AVR - even working down to the assembler level.
If you're making things that push an Arduino to the limit, or if your projects outgrow the normal Arduino-compatible boards, running out of program and flash memory space, or you're stacking on Ethernet and microSD shields, or all at once - it's time to upgrade to the Freetronics EtherMega:
Quite simple the EtherMega is the fully-loaded Arduino-compatible board on the market today. Apart from being completely Arduino Mega2560-compatible, it includes full Ethernet interface, a microSD card socket, full USB interface, optional Power-over-Ethernet support and still has a circuit prototyping area with extra I2C interface pins. So if your project is breaking the limits, upgrade to the EtherMega today.