I'm looking for a simple billing app.i would like it to work with my iPhone and on my mac at home. I shoe horses and i need to keep track of who owes and who paid. i also need a app that can keep track of horses needing done. example: if i do a horse today,i would like it to automatically set it up for 5 weeks or 6 weeks what ever i set it for. needs to work on iPhone and mac also. the billing app is most important but a scheduling app would me nice too. i got the iPhone 4s and iMac with lion. thanks for any help.