I think the 5.75% return is over the 48 month vesting duration, on the extra money you would have earned (and invested). So, the excess (per year) would be something more like (50(1.0575^3)+50(1.0575^2)+50*(1.0575^1))/4. (Though it seems I'm a little off, so maybe they do the calculation monthly or biweekly).
If you keep track of either the short URL or the long URL somewhere on your end, you can get the other part using bitly's link API: http://dev.bitly.com/links.html and the associated metrics with the link metrics API: http://dev.bitly.com/link_metrics.html -- Once you have that, you can write a simple app (or use any of the free ones out there) to provide the same service.
Or honestly, just pay the $700 if it's not worth the dev investment and provides a significant value to your service.
 Though be careful with that. Only refactor stuff if you're pretty confident about how it works, and that your changes don't decrease performance or readability.
> More than 15 percent of SSNs are associated with two or more people. More than 140,000 SSNs are associated with five or more people. Significantly, more than 27,000 SSNs are associated with 10 or more people.
That article is referring to corporate records, though, and leads with the fact that many people have multiple SSNs if you track all their commercial accounts as gospel truth. Does social security actually hand out duplicate SSNs, or is this all caused by people not remembering theirs/bad typing?
But when everyone has a $20 USB stick capable of mining 10k coins a month on today's difficulty, that difficulty will go up dramatically. Mining will always be expensive to everyone but those with early access to next generation hardware.