It's kind of hard to see. You may need to elaborate more on how you want it improved. Do you want it more quite or what do you think is wrong with it. Right now it looks like it's doing its job.
I think anything hanging out of the side of your tank is going to be an eyesore. You could replace the white PVC thing with a 90 and get it to go around the back side of the tank. Other than that I don't really have any ideas other than drilling a new hole in the back.
If it really bothers you then you could cap it off so its smaller and has no hose coming out and use different filtering, but thats a lot of work in my opinion. If it was mine I would just run pvc like trick said and just try to cover it up some how.
I agree with that. Go to glass-holes.com and check out their bulkhead/overflow combo...so sweet.
You could build an enclosure around the back and sides.