haha, i use that one all the time as well. I just hate that pop-up ad that they have... but otherwise a very excellent link.
AQadvisor is what i mainly use when i want to stock my tank, but i use the other link for figuring out how much actual volume i will have after glass thickness is taken into account. Its a little more exact for trying to figure out how much volume is left after application of glass sides for DIY projects that need to fit a shelf exactly, etc.
On another note, maybe not in the DIY section, but there should be a helpful links sticky somewhere with sites like this..