I found an old piece of paper on my desk today that had a list of several mining companies at the feasibility stage. In other words, they are looking at developing their exploration property into a mine. I think I compiled it a couple months ago so things may or may not have changed.

I have not done any research on any of them except for the fact that they are at the feasibility stage:

Gold     

GBG.TO [1] http://www.greatbasingold.com/gbg/Home.asp [2]
MGD.V [3] http://www.mandorin.ca/ [4]
AXM.V [5] http://www.axmininc.com/DesktopDefault.aspx [6]
VVI.V [7] http://www.valenciaventures.com/ [8]
MGM.V [9] http://www.morgainminerals.com/s/Home.asp [10]
BAJ.V [11] http://www.bajamining.com/ [12]

Diamonds

PGD.V [13] http://www.pdiam.com/s/Home.asp [14]

Nickel/Copper

CZZ.TO [15] http://www.canadianroyalties.com/en/ [16]

If you would like to add more and we could make a better list that would make this page a good resource for someone looking to invest in companies near production/cashflows/profits.