R4 for DS lets DS owners play homebrew
R4 for DS is a great tool for playing homebrew games. All you need to do is plug in an SD card with the homebrew files you download from websites. Then use your R4 for DS to run the games through. On top of this you can also run homebrew applications on your Nintendo DS. Some of these include office like suites with word processors and calculators. There are even applications which let you use your R4 for DS as a mobile telephone! This works like Skype and requires a wi-fi connection, but means you can get free phone calls.