I have held TGA for quite some time now and for the last 2 years it has sadly not done very well as you can see from it's 2 year chart, being flat to down.
Despite the track record of the last couple years on TGA the longer term track of light crude oil has been very bullish as can be seen on the 10 Year Chart.
Taking a look at the longer 5 year chart of TGA we can see that they indeed have had some good times and that was largely influenced by the price of crude oil.
Taking a look at the income statement we can see that it has been doing well in reality despite what the market price action is telling us. Net income went from $7,229 (2004) -> $20,573 (2005) (184% increase year over year) -> $26,195 (2006) (27.33% increase year over year). Not too shabby.
The income statement is the final product but it is more subject to accounting nuances so taking a look at the cashflow statement should give us some more insight. They have gone from $13,066 (2004) -> $39,357 (2005) (201% year over year increase) -> $47,383 (2006) (20.39% year over year increase). So, still 20% growth is not too shabby. Then, we can see where the money has been going and in the last few years it has gone from $21,689 (2004) -> $33,163 (2005)(52.34% year over year increase) -> $50,520 (2006) (52.9% year over year increase). These last couple years had alot expenses in exploring for new territories. Also, the Egypt concession was obtained and wells drilled to kick things off.
Now, according to this yahoo article "TransGlobe is the largest proportional holder of Middle East acreage relative to its market cap..." which places them in an enviable position for longer term growth. Also, the CEO Ross Clarkson has already built up a large company and so demonstrated his skill at doing so.
UPDATE 6/25/2010: Transglobe has finally moved up past it's $7 high (it's been a long slog) and now has a solid resource base in Egypt that is fully under it's control. It should keep moving higher on oil price increases and production drilling success.