Hey Sexxy,
I'll be in Ibiza Aug. 15 - 22. I know there's a ferry from Barcelona to Ibiza, but it's pretty long.
Check out these sites for ferry and other Ibiza information (I've found these sites very helpful in planning my trip there):
http://www.ibiza-spotlight.com/transport/ferry_i.htm
or
http://www.ibizaholidays.com
Have fun,
India