Exploring systems in Mass Effect 2

Is there any point in exploring systems that do not have a mission associated with them, besides resource gathering? For example are there any hidden side quests or random encounters to be found?

EDIT: To be more clear, are there any quests or random encounters which are not previously referred to or marked in any way, and thus can only be found by scanning planets? I have "found" a couple of missions by scanning planets but in each case the mission location was already marked on the system map.

Solution 1:

Yes, there are some side quests that are not marked. If you scan a planet and find an anomaly there, this means there is a mission on that planet.

They are pretty short, but somewhat more varied than the side missions of Mass Effect 1.

According to the Mass Effect 2 wiki there are 38 anomalies that each represent a side mission (don't follow the link if you want to remain unspoiled).

Solution 2:

If EDI does not tell you when you first zoom in on a planet that "an anomaly has been detected", the planet can safely be ignored.

Unlike in Mass Effect 1, there are no hidden objects to search for (i.e., carbonaceous asteroids) either.