Is there an App or Program that allows you to set specific timers?

I'm looking for an App on the iphone that allows me to create a timer of sorts. Basically I want to use it for an exercise routine I'm looking to do. Basically I want to set it for 30 minutes, but have intervals in it so that it alerts me when to change my exercise. For instance, say I want to try the 7-minute workout. The 7 minute workout has 12 exercises where each exercise is to be done every 30 seconds with 10 second rests in between. The program or app would basically alert you every 30 seconds then every 10 seconds until 7 minutes are up. Is there a program that allows you to do that?

Sure, try these:

http://timer.onlineclock.net/timers/

These are not apps that you need to install. You use them online…