If I were you, I'd think about these things:
- will the technology actually improve the performance of your campaign, or will you be forced to set endless rules on a keyword basis which isn't much better than managing it yourself by hand?
- will the technology give you insight into the opaque markets of G/Y/M by using your historical data to model performance?
- can the technology handle multiple metrics, e.g if you make a margin of 10% on one product and 20% on another?
- can the technology help you make reliable predictions and forward visibility, e.g. what will happen if I increase my CPA by 25%?
Technology providers to consider:
- Atlas Onepoint
- Bidbuddy (if you're in Europe)
- Doubleclick/DART Search
- Efficient Frontier
- Omniture SearchCenter
There are plenty of others. Let me add the disclaimer that I work for one of the above.