you know them all
Sound synthesising, 2d animation, for credits, etc.
heres the thing i do, i render a small bit of an animation in blender, export it into an avi (with compression the filesize with decrease a little/lot), then open up flash, import the avi, (even without compression the filesize would become 10% of what it was before, which is AWSOME) and then use flash to do all the cool transition effects.
i had a 43mb blender animation, (totaled all scenes), flashed it, and now its 3mb. and it looks almost completely the same.
sounds can be easily got from places like flashkit.com. and flash has this really usefull sound thing which shows on the frames so that you know what music is playing when, so that you can make your anim start on a really good position. this also simplyfies lipsync loads.
another good thing about this is that flash exports into .swf. .swfs can be viewed in a browser without downloading. you can also add loading bars and all that fancy stuff (i wont go into details but just search for actionscript stuff tutorials if you want that).
i would recommend using flash 6.
though the newest flash is crap, is does have some new text effects like blur out, explosion and other stuff which is great for showing the credits.
obviously you can export the anim to be viewed in flash player 5 and lower even though you are using the newest version. which is good for low users.
also, flash exporting (rendering) is much faster than blenders.
any comments about this is welcome. but dont expect many replies from me, i normally hang about the blender general Q&A.