Here’s a couple websites I ran across that you may find useful. The first site will convert traditional tunes into various dulcimer tunnings such as CGC, DGD, DAA etc. The second site will help you with playing Irish tunes, playing certain tunes slow, medium, and fast speeds.
1. Yet Another Digital Tradition Page: This website has a database of thousands of tunes and that will create a simple dulcimer tablature is http://sniff.numachi.com/aidx/aidxA.html. In the index when you click on a song title then click on “Dulcimer tab” and you can select the tuning you want to print the tab out in like “DAA” or “CGC” etc
2. Toraigh- Traditional Irish Folk Music: A website for trying to assimilate Irish tunes is http://www.toraigh.com/slowsessions.html . The tunes are played at three speeds, slow medium and fast. They are in the key most often used for the tunes, so you may have to tune the dulcimer appropriately to play along.