I'm looking for a free script that I can run on my own server to
manage and host images for my eBay auctions.  Ideally, this script
will have an interface wherein you upload a set of pictures, associate
it with a particular auction (not necessary as I would be fine with
just a standard non-eBay-specific script), and have it automatically
create thumbnails of the images, and HTML code which would display the
thumbnails with links to the full size images on my server.

I'm going to be running many auctions a month, and resizing and
uploading every picture individually, and then writing the HTML code
for each set of images is becomming very tedious.  I just need
something that will make this task quick and painless.  I'm willing to
tip generously if you can find something that matches my needs
extremely closely.

eBay won't allow us to add in script that use thumbnail, link, open
new window or anything like that because that would cause hi-jack the
page within ebay. We can't use onmouseover, onclick or <a href =..> at
all.
I was in the same situation days ago and I created a script myself
where I would enter the folder name and the script automatically
search for image and display image correctly, again: no link,
thumbnail or anything like that, just display the images on the page
About the HTML. I use Front page to list my item. It helps alot, I
dont have to edit HTML at all.
If you want to know more shoot me an email at luubao@yahoo.com
by the way, how much will you spend on this script?

For hosting eBay gallery is not possible.Ebay converts the picture
into thumbnail by it self. All you can do is provide URL for hosting
eBay Gallery URL.

Hope this helps.