I just stumbled across this while looking at the Shared Pictures on my MySite: Apparently you can filter any view on any list through the URL querystring by appending the parameters FilterName and FilterMultiValue.
So - if you have a list and view whose URL is, say
and for some reason* you want to show only, say, the items with ID 21, 23, and 24, you can use the URL
and the list will be filtered for you.
Note that it does not work well if your list has folders, and though you can use Filter columns other than ID, you may or may not end up with a "One or more field types are not installed properly" or a <!-- #RENDER FAILED --> error message.
This is not really a MOSS feature, best I can figure it's been baked into WSS since v2 (at least) - some documentation is here:
*not sure what this reason might be. YMMV.