Since we now have procedurally generated sectors, it can get a little confusing remembering where you've been and which system it was that had that cool thing you wanted to finish exploring, but didn't have the cargo capacity or time to do it earlier.
It would be nice, therefore, to be able to manually mark systems with a "Point Of Interest" icon. This could be implemented as an additional option in the drop-down list when you click on a system from the sector map, and could show up with an icon similar to those systems with a warning beacon attached.
That way the player can easily mark a particular system amid a cluster of confusingly similar stars, and be able to return to it at a later date with less hassle.
Thoughts?