vertically justify or how to vertical fill a div using css

Question

I have a page that have something like this:

<div>
<sometag></sometag>
<sometag></sometag>
<sometag></sometag>
...
<sometag></sometag>
</div>

Sometag may be another div or an img, but it has fix height, i guess it's not important. Also, the sometag elements are placed one of the top of the other. The height of the div is a little bit higher than the sum of height of sometag elements. How can I "vertically justify" the sometag elements within the div? The first sometag must be at the top of the div, the last one at the bottom and middle ones must be vertically equidistant of eachother.