I just stumbled across the Play Submissions Helper-- and have stumbled across them before. They offer an online compendium of listings for playwriting opportunities. Over 400 entries by their count. My question is, for 19.00$ a year, is it worth it?
If you get a contract, probably worth the price. Playwriting opportunities is not the same as play publishing. Playwrights Forum and The Burryman website have plenty of submission opportunities. Having a play produced is not the same as having a play published, nor is it a guarantee of getting it published. All depends on your goal.
My experience with them is that they practice deceptive advertising - they have a teaser rate which they will increase without warning via a recurring paypal payment which they also don't tell you about ahead of time. It's not terribly valuable information either, as 90 percent of the opportunities won't pertain to you or can be easily found for free if you follow off-Broadway theaters and the like. Buyer beware.