I found a great little tutorial from AudioTuts+ about editing all your takes at once using Apple's Logic Pro 9 recording and mixing software. This tutorial reminded me that you can also do the same thing in Reaper.
One of the many differences between Apple's Garage Band recording software, and Logic Pro is the ability to record multiple "takes" of something. That means that you can set a region in your song to loop while you record take after take of the same part. This is awesome for particularly difficult vocal or instrument parts. Each time the region loops, a take gets recorded and saved. When you've recorded as many takes as you feel you need to, every take is visible on the track. You can even divide that audio region in segments and pick the best performances in each segment to build the perfect part.
The tutorial I mentioned will show you how to apply certain edits so that they apply to every take simultaneously.
By the way, this exact thing - recording multiple takes and having them all visible on the same track afterward - is a feature of Reaper recording software as well (which is available for PC and Mac). You simply record your first take of a track, rewind to the beginning and record your next take. You can also use the loop function like I described above for Logic Pro. Just highlight your region (you want to make sure to put enough time into the segment as a lead-in for each time it loops), click the "Toggle Repeat [R] button," and start recording take after take as above. You can also composite (build from bits and pieces from all the takes) a perfect take from region segments just like in Logic Pro. To view all the takes in one track, make sure to hit Ctrl L or choose Options, Show all takes in lanes (when room).
We have a 19-video tutorial course on audio recording with Reaper - The Newbies Guide To Audio Recording Awesomeness 2: Pro Recording With Reaper for $47.
The Logic Pro tutorial can be found here: http://audio.tutsplus.com/tutorials/mixing-mastering/how-to-edit-all-your-takes-at-once-in-logic-pro-9/