http://www.seattleavionics.com/iPhone.aspx (http://www.seattleavionics.com/iPhone.aspx)
It's free, and has great information about airports and weather.
For a place called Seattle Avionics Software... you would think they would have a different location in their screenshots.
Love this app! Everything contained in one app. The weather feature are the best of this app. pulling TAFs and METARs from surrounding airports even winds aloft. Definitely a +1 in my book. Also having zulu time next to local time at the top is an added bonus. Would be the perfect app if they added approach plates to it like fltplan.com's app.
Seattle Avionics makes an awesome PC app called Voyager.