Welcome to the forum for my Bengali alphabet course: http://www.memrise.com/course/1104265/bengali-alphabet-baanlaa-brnnmaalaa
If you find any mistakes, please share them here with me, I’m happy to fix them.
Should you be a native Bengali speaker or know some, please check out Forvo’s pronunciation archive for Bengali and feel free to share: http://forvo.com/languages/bn
Once enough high quality audio files have been recorded, I can add them to this course.
Hi, I just featured your course on the Bengali course I’m creating at http://www.memrise.com/course/1192787/learn-bengali/
Oh wow! I just came across your profile, you’re a German who’s interested in learning my native language! Cool!
Hi! Cool that you create more courses for people who want to learn Bengali! Nice, easy and playful courses on platforms as this, Quizlet or Duolingo are almost not existent. What’s missing in my opinion even more are audio files - please check out Forvo, all audio uploaded there can be used by anyone for free courses. 
Yeah, I am aware of Forvo. I have contributed to record some audio. I’m pretty much sure though that pronunciations of all of the letters of the Bengali alphabet have been already recorded by native speakers and are available on Forvo. And of course I invite you to try my course. It is incomplete yet, but you can have a look, provide some feedback: [Course Forum] Bengali from English: Opinions, Queries, Recommendations. To be honest I’m looking for some commonly used simple phrases that I can add. If you want to add any phrase of your choice you can post it there. I am really looking forward to you. 
And yeah, I had applied to contribute for the English-Bengali course on Duolingo, but haven’t received any reply from the moderators yet.