A Canadian oil sands play. In the recent past, and at somewhat lower levels, I've heard this recommended by Jim Rogers, T. Boone Pickens, and Charles Maxwell. I don't know about you, but I'd say these are three guys who know a little about oil and making money.
The basic idea is that the company has a huge amount of potential oil reserves in it's oil sands, with the added bonus that it's close nearby and in a fairly stable country. [Though you never know when one of their politicians is going to get a kink in her skirt and call our President an idiot, but I digress. Thank God they have democracy over there or ...]
Oil sands are apparently just what they sound like, a mix of oil and sand that must be mined and separated to produce a lower grade of crude oil. The catch is that the process is seriously energy (generally natural gas) and water intensive, dirty as all get out, and has significantly higher costs than regular oil wells. However, as oil prices rise and stay elevated (above $35 is particularly good), oil sands become cost effective and profitable.
(Disclosure: I own no SU, though I plan to buy it at some point in the next 6 months.)