a lot of it depends on just how much power you really want, and if you WANT to spend $3000. If you WANT to, it is very easy to do.
if you are trying to hit $3000 then here is my suggestion:
http://www.newegg.co...N82E16819115225 - intel i7 930 - for $290 its cheap and OC's well. This is an easy place to save a few bones for other places, and still wind up with a heckuva rig.
http://www.newegg.co...N82E16811119197 - Coolermaster 922 case. They are roomy, and quiet. While I have mostly Antecs at home, the Cooler Master is a definite nice choice. $90
http://www.newegg.co...N82E16835103055 - Cooler Master v8 CPU cooler. If you are going to OC, and why shouldn't you? Get a cooler than can handle the stress.. The V8 is a proven beast. $60
http://www.newegg.co...N82E16820148254 - Crucial Balastix 6GB 3x2GB @ 1600Mhz with 8-8-8-24 timings. These should do you well, and you get plenty of room to play in. $173
http://www.newegg.co...N82E16813131642 - Asus Rampage III extreme mobo. USB 3, Sata 3, 4 way xfire/sli - a very high end board. and pretty too! It even matches the case (come on - cosmetics count! lol) - $370.00
I am very particular about my Power Supply in my gaming rigs.. as such:
http://www.newegg.co...N82E16817703028 - PC Power and Cooling Silencer 1000. It will take any OC load you feel like, and still let you run a couple or few of today's most demanding cards. - $250
Then comes the part that is hard to really decide on. The video card. I say grab the ATI 5870 because it is very powerful, and still manages to produce less heat, and less noise than the latest Nvidia offering (about 20C cooler - or more!) I don't care what brand you go with - but get the phoenix shroud! The phoenix shroud was actually over engineered for the card - allowing a very high OC on the stock cooling.
http://www.newegg.co...N82E16814125322 - $500
Then you haev your hard drive and optical drive choices from here... and this all depends on your taste. I would say, grab a velocirapter, as they will provide plenty of every day performance without blowing the budget, or sacrificing other parts.
now, that right there puts you at $1730 plus your drives (figure about $320 if you choose the Velociraptor 300gb + a storage drive at about 1TB - and about $100 if you want a blu-ray reader/dvd burner) so if you really want to hit $3000, you can grab two of the video cards for an extra $500, double the ram even... or go with a nicer case - like the Lian-Li's.
so there you have it, a way to hit $3000 with a rockin rig.