it can be done without any special software as well. By default any downloads from the browser will go to sdcard/downloads. Then just play that ringtone in the music player and go to menu>set as ringtone. From then on that rintone will show up in all the ringer settings menus.
Not as intuitive as an app might be but can be done without one.
the zedge app worked except i have to download whats on zedge. My issue is, if i download a file from the phone (mobile internet), how come it doesnt ask me where do i want to save (sd card)? Am i missing something?