Generate image styles with a rule on "node save"? This QA has some discussion about the lazy image loading.  Imageinfo_cache is D6 only at the moment, and rules_image_styles apparently runs on every node view which isn't great for performance.

Wouldn't it be possible to just create a rule that fires "on node save" and for all types that include images you'll execute PHP code to generate all image styles?
There seems to be a third module that has this ability already, however it doesn't seem to be compatible with Rules just yet. It is compatible with Trigger however (I don't know if this allows it to be automatically compatible with Rules...let me know if you find out how). Here is the module: http://drupal.org/project/ispreg