Six Sigma Green or Black Belt- Gives you a good business stats backround and improves your ability to lead teams.
CFA- Very hard to get. Requires you to have no life for 3 years, but the payback is big. Easier to just go get a masters in finance.
Statistics.com has an advance business stats certificate program.
Excel- A must. Pivot tables are probably the most used Excel function, so its a good one to learn. Good to learn Visual Basic too.
Minitab or a similar stat program
Economic indicators- Good to understand these indicators and where to get the data. Wharton School of Management has a good book out on this. You can pit alot of this data against company specific data, which can help you understand company specific trends relative to what's happening in the economy, which can help you help your managers to plan ahead, which will make you very valuable.
History- reading history, both economic, general business, and industry specific can make you wiser than your age.
Good writing skills- understand the basics of good writing. If youÃ¢â‚¬â„¢re a bad speller like me, than utilize spell check a lot! Even though writing technique is nothing and originality is everything, your peers do not think the same.
Strategy- read the Art of War and Michael Porter books. Don't do SWOT, because a 1st grader could do it and its static. Also, Henry Mintzberg's The Rise and Fall of Strategic Planning is a good book. There are a lot of strategy books out there and most of them are not worth your money. Other notable books are: Scenarios The Art of Strategic Conversations, Thinking Strategically and War and Decision. War and Decision is not a strategy book, but it gives great examples on how to strategize. Marine Corps books on leadership, strategy and tactics are good and contain a lot of wisdom.
Talk to important and successful people. They have a wealth of knowledge.