The attached pics show the Sony official horizontal stand I modified to contain a madcats slim mutitap, HDD fan made from a 60mm CPU fan, USB card reader/combined hub, made by Vakoss (model# TC-R723-UK).
The card reader/hub is compatible with SMS, ulaunch elf and sony USB devices. (eyetoy etc.) It also is USB 2 compat for PC use. I made the hub removable so I can use it to read all the flash cards I have when I travel.
The stand is secured to the PS2 by way of hot glue "pegs". I removed the rubber feet on both the PS2 and the stand. The hot glue pegs in the back were made from a makeshift mold so they would fit into the holes the the rubber feet were in.
The multitap bottom was removed and I drilled some holes in the stand and attached it by means of longer screws into the multitap's original screwholes.
To find were the HDD vent holes should be drilled, I used the holes in the HDD cage as a template, scribing the position with an ice pick.
The fan is powered by the 5V of a USB cable I soldered a 3 pin connector on to. It is attached to the stand by hot glue. Space was left underneath it so the air can exaust.
One of the USB cable's plug end was modded to be a right angle to the right by disassembling it and bending the housing to the right and hotglue applied to the outside. In the future the USB cable ends will be modded to turn left.
These mods are purely functional, work well, but are not exactly "pretty".
If you would like to do any of these mods and have questions, feel free to inquire, and or post your results here.
Update: I have recently fixed my right angled USB cord to go the left and under the PS2. I have also velcroed the stand and the case together so it stays on during transport. I'll have new pics soon of the changes.