Alternativeto is a great web resource that allows you to find either both free or commercial alternatives to your favourite piece of software. For instance when I searched for a free alternative to Nero Burning ROM AlternativeTo offered me 15 alternatives.
You can filter by platform and all software is rated by users to see what is worth downloading and what is worth leaving behind.
I will use this quite a bit over the next few months as I put together a new image for our 200 new machines arriving at the end of the year. Check it out for yourself here.