I wrote a fuzzer "dumb fuzzer" and used a sample from http://www.ccp14.ac.uk/ccp/web-mirrors/bca-spreadsheets/scanplot101.xls  which I randomly found on the internet. I mutated the data and tested roughly 1000 cases on several Document Reader Applications for iPhone. 

http://www.exploit-db.com/sploits/goodreader_poc.xls