As a vertical stand, nYko's
PS2 Vertcial Tower has a problem. If you install it exactly as the instructions explain, the tower storage unit will rock back and forth easily. This can easily be remedied by using the two additional foot-connectors to connect the top (in upright position) feet to the nYko tower. These connectors are modified replacements for the feet on the PS2, and are exact fit replacements. It is possible that removing these rubber feet on the PS2 might void the warranty, but if you put the originals back I'd love to know how anyone could ever tell.
In the storage catagory, the PS2 Vertical Tower racks up. It has 6 individual slide out trays that look much like the PS2's own tray. These trays are spring loaded, rather than motorized, however, and have storage room for a single disc on both sides of each tray. Altogether, this makes 12 storage slots for your discs. Additionally, ther is a small triangular area on the opposite side of the PS2 Vertical Tower which is designed to hold up to three PlayStation or PS2 memory cards. This helps keep your memory cards withing reach.