While "sales" might be something of a bad (or at least awkward) word on Twitter, "referrals" is not. In the context of learning, networking, and sharing (rather than buy, buy, buy), business referrals can provide real value--and ultimately a real ROI. Jim Milton, director of corporate strategy at SelectMinds, told me in a recent interview that one of the first places companies should look is among their current and former employees. "The business development use case with corporate alumni is definitely a proven one, and something where you can measure tangible results in terms of sales, especially in the B2B space," he says. Even if you don't have a formal corporate alumni network, following former supervisors, colleagues, and direct reports can keep you in the loop on what they're up to and how that might translate into mutual opportunities. (The image above is an example of how Microsoft's alumni use Twitter to promote and connect philanthropic efforts.) Twitter's Lists feature is a good tool in this regard. The integration with LinkedIn can help, too.