First in line for the line-up of compounds is from Zalman. This is their ZM-STG2 "Super Thermal Grease". It has been around since some time in 2006 and retails for just under $10 U.S. at Newegg.
Next up we have MX-2 High Performance Thermal Compound from Arctic Cooling. This compound has been around for a while as well and rings in at the register at around $8 U.S.
When I did the coolers for Noctua, they also supplied me with a sample of their own TIM with this tube of NT-H1.
This is a TIM that needs no real introduction. AS-5 is almost the industry standard and is what I see recommended most in the forums. AS-5 has been around for what seems like forever and is what we use exclusively in our T.E.C.C. CPU cooler testing.