One analyst prefers a broad-based ETF focusing on energy, metals and agriculture. Diversification of this nature are found in PowerShares DB Commodity Index Tracking Fund (DBC) and the note, iPath Dow Jones-AIG Commodity Index (DJP).
A list of all commodity ETFs and ETNs can be found on Seeking Alpha.
When it comes to energy ETFs, exercise caution.
Always knowing the risks is key, though. The more specialized an ETF is, the harder it can fall when the momentum is over. Commodities are volatile, and there’s been talk that he sector is in a bubble. Having your exit strategy will protect you.