How can I accelerate a rigidbody towards another at X m/s?

I also only want to have to add the script to rigidbody B

I don't know your setup or goals, but doing it this way makes your code pretty ugly.

X would exponentially decrease as the distance increases

Consider a linear rather than an exponential decrease. It may feel/look better to the user.

@robertbu, the reason it has to be exponetial is because i am making a realistic space flight simulator, similar to $$anonymous$$SP and looks/feels are second to realism in my project. As for me only applying the script to rigidbody B, i dont want to have to add it to every other object

in update:

transform.rigidbody.AddForce((locationA-locationB) * $$anonymous$$assOfThing)

and depends what you consider a meter

by meter, i mean 1 unit in unity

If you looking for realism then you'll have to have realistic scale and mass. Here is a link about planetary gravity:

http://answers.unity3d.com/questions/359759/how-to-program-gravity-for-planets.html