I`d agree with the TUSL2 - I have the Pre-tualatin CUSL2 which has to be the ultimate Intel based OC board for coppermines and Ive yet to see a board with more USB ports (7) - BUT from what I remember they removed the Voltage control from the TUSL2 version ..
If you want 1Mhz FSB adjustment, enough PCI slots, totally stable operation (With a VIA!!) and the ability to run the RAM Async (though still no CPU Voltage adjustment) why not save a whole wad of cash and get a Jetway 694TAS? - £50 (probably $50 in the USA), it`s based on the VIA 694T Chipset, has a brilliant BIOS, the AGP actually works well unlike earlier Apollos - I hit 1400 at stock voltage with one of these from a 1200 Celly, was able to run the RAM @ 150Mhz for a noticable speed increase and it doesn`t have the ATX pwr connector in a stupid place... I hated previous VIA chipsets to the 694T (loadsa problems especially with AGP) - and performance wise I can`t say that I`m overimpressed with the i815E either (512Mb RAM limitation, no running the SDRAM Async @ 133 when the CPU is at 100 etc) but the Asus boards definately make the best use of this modernized but Crippled BX..