mega rs485 serial available
http://forum.arduino.cc/index.php?topic=134980.0
http://www.gammon.com.au/forum/?id=11428
http://arduino-info.wikispaces.com/SoftwareSerialRS485Example
https://forum.sparkfun.com/viewtopic.php?f=32&t=34205
http://my.safaribooksonline.com/book/hobbies/9781449399368/serial-communications/introduction-id3
http://boards.straightdope.com/sdmb/showthread.php?t=679163
*libelium:http://www.geek-workshop.com/thread-297-1-1.html
http://www.libelium.com/development/waspmote/examples/
ftp
http://www.cooking-hacks.com/documentation/tutorials/arduino-3g-gprs-gsm-gps#indexz
http://forum.arduino.cc/index.php?topic=178607.0
http://www.cooking-hacks.com/forum/viewtopic.php?f=29&t=3415
http://www.libelium.com/development/waspmote/examples/gprs-20-uploading-files-to-a-ftp-server/
http://playground.arduino.cc//Code/FTP
http://www.cooking-hacks.com/documentation/tutorials/arduino-gprs-gsm-quadband-sim900
http://www.amobbs.com/thread-5481789-1-1.html
http://www.geek-workshop.com/thread-2695-1-1.html
http://www.geek-workshop.com/thread-297-1-1.html
龙戈电子旗舰店:
各种基于Arduino的传感器
http://auto-ctrl.taobao.com/category-387473725.htm?search=y&parentCatId=265641441&parentCatName=%A1%EE%B9%A6%C4%DC%C4%A3%BF%E9%A1%EE%CF%B5%C1%D0&catName=Arduino%D7%DB%BA%CF%C4%A3%BF%E9%D2%BB