No Ringtone limit iOS4 (tested on iPhone 4) No Jailbreak Required...

Software used:
http://www.macroplant.com/iphoneexplorer/
http://audacity.sourceforge.net/?lang=en
http://www.apple.com/itunes/

sorry for my voice. im sick :p normally i talk much clearer.... and with less of an accent.

Guide:
1 Make a random sound clip under 30sec save it
2 Add it to your itunes library
3 right click the soundfile and click "create ACC version"
4 go to "username"my musicitunesitunes mediamusic in one of the
folders there will be a music file called "something".m4a e.g. random.m4a
5 cut this from your folder into a folder under music e.g. ringtone
6 rename "filename".m4a to "filename".m4r, add this sound file to
itunes. a tab named ringtones will be added.
7 now go to you iphone tab in itunes and select the newly appeared ringtones tab.
8 Select sync ringtones
9 sync
10 start iphone explorer
11 go to mediaitunes_control
ingtones
12 copy the files from the folder. into the folder you created under music
13 create acc version of the music you want to use as your ringtone
14 test the files in the folder under music to see which is your ringtone e.g. MISJ.m4r
15 Delete the tested files from your itunes ringtone lib (keep the original)
16 rename your ACC version of your desired ringtone to the name of your
ringtone from the folder under music. e.g. MISJ.m4r
17 drag and drop it into the iphone explorer mediaitunes_control
ingtones window

18 GO to settnings and select your ringtone (they appear at the top of the window)

I discovered this...