Ask HN: What customer can do regarding heartbleed bug?

It seems like many sites are affected by heartbleed bug and some quite popular (used as infrastructure) are not yet fixed. And since all these systems are interconnected, security problem in service X might cause problem in service Y even if service Y does not have this issue.

So the question are have the following:

- How serious is this problem?

- What one needs to do to minimize impact on his/her own security?