I'm not sure how many people have heard of Abandonia, but for those who haven't heard of it or have forgotten, it has a lot of old DOS games that are considered abandonware and are free to download.
http://www.abandonia.com/
I have found several old favorites of mine like the
Quest for Glory series and
Conquests of the Longbow. Give it a look and see if you find anything you like.
And be sure to get DOSBox as well if you find any games you like.