Indeed. It took me a moment to figure out and then verify that the concept is centered on donating blood. There are certainly several clues about it, but it seems like (just intuitively) the site would increase its chances of signups if the purpose were stated upfront and clearly.
High time smartphones are used in healthcare and other such social ventures. This can become a one-stop solution for Blood and maybe even Plasma requirement, which is a huge problem in many developing countries.
Personally, I have experienced situations where my friends and acquaintances had immediate requirements for blood, and Bloodline, I feel is the one stop shot for it now.
These guys have indeed tried solving a critical problem in developing countries. Keep up the good work!
"We match people who need blood with those willing to give it."