Hi Nick,
The first step in ncreasing your marketing ROI (if you haven't done this already) is in defining the metric(s) by which you'll judge marketing effectiveness. This variable might be sales, clicks, site visits, newsletter sign-ups, product trials... whatever metric is the best indication of marketing ROI for you.
Then you need to analyze your marketing efforts according to this metric, increasing ones that generate strong results per dollar invested for your selected metric, and reducing or eliminated marketing efforts which are generating poor results per dollar invested for this metric.
Given the current economic climate, you might have some leverage to renegotiate some of your marketing contracts according to their performance and your ROI.
Best,
Uriah