it is not possible to have more than 50 Pictures in your Online-Photo-Album.
The 50 image "limit" is just a recommendation, and an old one.
There is no absolute limit, so you can create albums with 100's of images. It's just that it gets slower the larger the albums is.
However, since we added that recommendation we've sped up the build process, so even a large album is made failry quickly (in less than 30 seconds, which used to take minutes).
But if you have 1000 images, you'll probably don't want to use online jAlbum.
You can always create multiple albums, instead of "folders".
Implementing a full blown online version of the desktop client isn't on our short term todo... We don't have those resources...