FitNotes is a fitness app aimed at weight lifting/body building. You can track number of reps on individual exercises, view progress graphs, record body weight, even keep notes about the day. FitNotes - Today
Custom Exercises

One of the great things about FitNotes is the ability to create custom exercises. The default set exercises has a lot of the basics but I've found that I needed to add a few exercises. When you add an exercise you can specify the name, weight increments, and even notes about that exercise. Each exercise keeps track of reps, and weight. If you set a new maximum weight/reps a trophy will appear next to that rep (see below).

FitNotes - Exercise
Rest Timer

One of the handiest features of FitNotes is the rest timer. After you add an exercise you can start a rest timer either automatically or with the click of a button, and this will give you a specific rest period. This is also great for motivation when you hear the alarm go off, you know it's time to lift.
FitNotes - Timer