If you place a program shortcut in the user's SendTo directory it will appear in the right-click SendTo list. I did a search on SendTo and in my case it is here:
C:\Documents and Settings\Dan\SendTo
This is a hidden directory so you will need to have the file visibilty & search options enabled to see it.
I tried this with PIXresizer
Bluefive software : useful freeware Windows utilities but it ignores a command-line filename parameter. Many programs will load up a file this way though, so search for a another small resizing utility. I believe that programs that work this way will also load a "drag & drop" file.
XnView works. You can use the Shift-S hot-key to resize a loaded image
Dan.