I am a bit of a "global warming skeptic" for many reasons.  I simply don't believe the "science" behind the theory is all that solid. 

Updated 3/20/07

Much was made in recent weeks about the UN report that blamed humans for warming trends in the 20th century.  It is interesting to note that scientific proof is not determined by "consensus" as was done with this report.  Just because a majority of people believe something is true, does that make it so?  Hundreds of years ago, the majority of "experts" thought the Earth was flat.  They also thought the sun revolved around the Earth.  Did that make it true, simply because a lot of people thought it was so?  Of course not. 

In fact, there are many dissenting opinions on the "consensus" reached by the report.  These of course are not given much press. 

Anyway, one of the common dissenting opinions points to the fact that increased global temperatures coincide with periods of increased solar activity – which the sun is currently going through.  Further, recent studies show that Mars, Jupiter and Pluto are also experiencing "global warming."  Coincidence?  I don't know but it seems unlikely.  Check these out for a bit more info:

http://news.xinhuanet.com/english/2007-03/14/content_5845252.htm

http://www.space.com/scienceastronomy/mars_ice-age_031208.html

http://news.nationalgeographic.com/news/2007/02/070228-mars-warming.html

http://www.heartland.org/Article.cfm?artId=17977

UPDATE:  March 20, 2007

 Two items in the news today that I find interesting:

 Researchers Question Validity Of A 'Global Temperature'
http://www.sciencedaily.com/releases/2007/03/070315101129.htm

Scientist who alleged Bush administration muzzled him, admits to doing 1,400 media interviews…
http://washingtontimes.com/national/20070320-120435-3136r.htm