I nuke my chocolate all the time to melt it - I'm 'stovetop double-boiler phobic' when it comes to this, as I had a horrid experience in a catering kitchen with about 10 lbs of Callebaut chocolate - don't ask!!
I just cut the chocolate in pretty small pieces, scrape up all the 'shaving's you get from chopping, put them in a pyrex bowl, and nuke for about 3 minutes at medium heat. I 'pause' the setting at about 1 and 2 minutes, to stir and see how the chocolate is doing. You can stop the nuking even if the chocolate still has a few lumps, and just keep stirring; the heat of the chocolate and the dish itself with finish the melting.
Microwave melting is easy, if you just remember - 1) don't 'blast' it; 2) check it regularly; 3) take if out when you have just a few lumps left.
I've even used this method to temper, and it works just fine.