Idea1: print Marketing
Buy a mailing list from a trusted source and send out customized flyer/postcard to your target audience (i.e. 5 mile radius of clients making over 100k per year). Have one flyer/postcard sent to 50% of your clients and the other postcard/flyer sent to the other 50%. Each post card can direct clients to two different website pages. Measure the return from each by finding out which post card drew the most audiences.
Idea2: Online Marketing
Run a survey of two keywords/phrases that already have high response rates on major search engines (i.e. google). Build a PPC campaign for each phrase and track how many come to the site on each keyword.
I do this for a living and find it often easier to think of something for someone else more than I do for us

Hope this gets you started?
Additional Thought: Buy two newsletters for your industry and mail them to target clients. Track response rates on each one as long as they are under the same controlled environment.