This is true. You want to find someone who is productive. That or you do like I did and find someone who loves what you love and then just make it happen yourself.
My tips for research:
1) look for clinical projects because these are faster. Lots of chart reviews and whatnot
2) get to know residents and ask about posters or orals that were presented but never written up. Ask to write them up in exchange for second author
3) case reports - keep your eyes peeled. When on your sub I or electives and you see a case everyone says is cool, write it up.
4) ask upperclassmen who the more productive PIs are and get to know them.