I can understand where you are coming from, but eventually, the resume and cover letters will need to be sent out, regardless of when that may be. How could it not be beneficial to get a list (that can always be added to and altered as interests become clearer), so that there is that much less that you have to do when the time comes to start the job search? It's something you can do at home while watching tv or at work when you're board, but will save you lots of time in the end.
In response to Bluff, I kinda started this already in an excel spreadsheet, and I also included a column for firms that have current Alumni from my schools (undergrad and law school) and the areas of practice. This way when the time comes, I can have cover letters that can make a connection with a memeber of the firm, and if I decide after taking a certain class that the area that a firm specializes in is not for me, I can simply erase all firms that specialize in that area.