MET TOWER INSTALLATION
WIND TURBINE TRANSPORTATION
CIVIL CONTRUCTION & CRANE PATHS
WIND TURBINE FOUNDATIONS
TOWER ERECTION
TOWER WIRING & INSTALLATION
COMMUNITY BASED WIND PROJECTS
First, let's review a quick rundown of the growth of domestic and international wind markets.
Wind power capacity growth by year:

As you can see, global installed capacity for wind energy has grown 482% over the last seven years, from 14,604 MW in 2000 to 84,934 MW in 2007. Broken down further, the international wind industry has a compounded annual growth rate (CAGR or year-over-year) of 28.6%, which is impressive, to say the least. But the past performance of the wind energy stocks is going to do little to help the future performance of your portfolio, apart from establishing an historic trend and highlighting what you've been missing.
Global Wind Energy installed capacity forecast, going out to 2012:

This data reveals that the industry will grow 215% between 2007 and 2012, from 84,934 MW to 267,837 MW. That's a CAGR of 25.8%
This is the type of information that can give your portfolio a boost. In an industry that's doubling in size every four years or less, there are surely more than a few companies worthy of investment.
The only thing left to do is to actively seek out the best ones.