We've all heard the importance of figuring out what's important versus what's just urgent.   Steve Pavlina wrote about another way to distinguish important from urgent and as an EMT, it's one I could immediately relate to.  Medical workers responding to a disaster triage victims into: [quoting from Steve Pavlina]

1. those who will die anyway whether they receive medical attention or not,
2. those who will survive anyway whether they receive (immediate) medical attention or not, and
3. those who will survive only if they receive timely medical attention.

Steve Pavlina suggests you can put your tasks into the same type of buckets.

1. Projects that will fail to have a significant impact whether you do them or not.
2. Projects that will succeed anyway whether you do them or not.
3. Projects that will have a significant impact if you complete them in a timely manner.

And then obviously you should concentrate on the third type – projects that will have a big impact if you work on them now!  The important ones that depend on you.