Okay, so at some point as a web designer you're going to come across a project where you have to design some kind of gallery with image thumbnails. 

In an ideal world (e.g., Photoshop), all of the thumbnails will be precisely the same size, so plugging them into nice little skins (the "pretty" that you put around them) is cake.  Unfortunately, the real world ain't like that.  In the real world, you have hundreds of thumbnails to deal with, none of which will probably ever be exactly the same size.

Now, of course, the thumbnail skins still have to work.  So what should you do?

The first thing to NOT do is hard-code the "width" and "height" attributes of the <img> tag.  Super bad idea.  Okay, not a TERRIBLE idea, but it will inevitably lead to some funny looking thumbnails as the img tag will stretch or shrink your image to fit these values.

So what's the alternative?  Well, ideally, you'd be using Coldfusion 8 and could use the super-cool built-in image manipulation tools to properly scale and crop every image to be the same size.  Ah, but we're not in an ideal world!

The second alterative I've found that works to a limited extent is CSS based.  It's pretty simple, really.  Take your img tag and wrap it in a plain ol' div and class it.  In the style rules, size the div to a fixed size–this will give you a great frame to work with.  At this point, images larger than the div will overflow it, but no big deal.  Simply use "overflow:hidden"–this will make any part of the image that explodes the div hide away.

Okay, so there's obviously some big drawbacks to this less-than-ideal method.  First, it pretty strongly presumes that all of the thumbnails are more or less the same size.  While it will still work with super-big images, the section of the image that happens to be visible in the div is all you'll see, and this may not be relevant to communicating what the picture actually is.  Second, if images are smaller than the containing div, you'll have some background-showing-through-the-containing-div issues to work through.  Nevertheless, if you have a bunch of thumbnails that are more or less  the same size, and you're able to compensate for images that don't fill the entire frame, this is a super-easy way to skin thumbnails without distorting the images.