I’m still working on a gallery plug in for Joomla 1.5, with my friend. We still have some small bugs to fix and do some real-world testing.
AdmirorGallery is basically evolved from Simple Image Gallery plug in. But instead of always creating the thumb for every user, we use something like a cache system. If there is no thumbnail (new gallery) we create the thumbnails in thumbs folder for that gallery
By doing this we overcome the limitation of Simple Image Gallery of recommended 40 pictures in a gallery.
Well until we finish it, you will just have to wait.
Here is a sneak peek of the gallery plug in