I wrote a module for Oddmuse that extends the markup to allow dynamic generation of thumbnails for images.
Here are some syntax examples. It is pretty much the same as wikipedia markup.
No parameters [[thumb:Lock_nut_pic]]
With optional comment [[thumb:Lock_nut_pic|cool comment]]
Using the optional parameter 'frame' (or 'thumb') generates a floating box. Your style sheet needs to have certain things. This will look similar to wikipedia. It aligns to the right by default. [[thumb:Lock_nut_pic|frame]]
Aligned to the right [[thumb:Lock_nut_pic|frame|right|lock nut comment]]
Aligned to the right and reduced in size [[thumb:Lock_nut_pic|frame|45px|right|lock nut comment]]
Aligned to the left and reduced in size [[thumb:Lock_nut_pic|thumb|40px|left|this is a comment]]
Multiple images in a row, reduced and aligned to left [[thumb:Lock_nut_pic|thumb|40px|left|pic1]][[thumb:Lock_nut_pic|thumb|40px|left|pic2]][[thumb:Lock_nut_pic|thumb|40px|left|pic3]]
[[thumb:Lock_nut_pic|left|this is a comment]]
[[thumb:Lock_nut_pic|right|this is a comment]]
Using 'none' - stops text wrapping around the image [[thumb:Lock_nut_pic|none]]
[[thumb:Lock_nut_pic|none]]greedy check]]
[[thumb:Lock_nut_pic|none|40px|comment]]