link2sd allows user apps to be linked to the SD card. in a nut shell, the apps are on the SD, but are symbolically linked to the system memory. this means that the apps use a fraction of the memory that they would normally, and if they are linked, then they mount alot faster after a power off or reboot. i have almost 60 apps installed on my phone, and everyone that can be linked are. i still have around 50mb free internal memory. widget apps can be linked and still work properly, and apps that cant be moved normally can be linked to save space. link is your best option with that app, it moves the lib, dalvik, and data to the SD, only leaving tiny size links behind in the internal memory.