Wanted to start a discussion to see where there are problems to be solved.
Here are some issues I've had in the past:
cost-per-click is too high - need cheaper keywords
Ad Click-thru rate too low - Need better ads
Landing page conversion rate too low
Need more volume -- CTR too low or trouble finding new keywords
Landing page doesn't match all of the different ads being tried, not dynamic enough
Adwords interface too complex