I was wondering:
1. what size frame sliders and swingarm spools I would need for my 2006 GS...IF I ever drop it (knock on wood) I want to try and protect my bike as much as possible.
2. what size bar ends would I need if I wanted to switch them out? And are the aftermarket ones as heavy as the OEM ones? And does it matter with the weight?
3. what are my choices for turn signals? (stock ones are killing me with the light on a stick thing)
4. is there any other mods I can do to make my GS look more "aftermarkety" (yes I know it's not a word!)

Thanks to anyone who can help me 

wow, 4 questions at once!    

I'll throw my 2 cents in.  

1.  There are no swingarm spools that will bolt onto any GS500 (E or F) swingarm without some form of modification.  Some people drill a hole, some weld a tab.  Dunno about F frame sliders since I have an E.  

2.  Don't know what will bolt on since I use aftermarket bars.  What I do know is that weight can make a big difference.  Most generic aftermarket ones are aluminum and lighter than stock.  If you feel vibration in your bars with your current setup, using lighter bar ends will probably add slightly more vibration.  

3.  Lots and lots of choices for turn signals.  Check the wiki or search the web for aftermarket ones.  Keep in mind if you decide to run LEDs at all 4 corners you will also need an electronic or LED approved flasher and a diode for the indicator bulb.  A set of resistors will work as well, but it isn't as clean of an install.

4.  Check out some other people's rides.  There are some pretty clever mods on this board.  

Sorry it's not much but I figured I'd throw it out there.  

I have been thinking of doing frame sliders also for my bike but haven't spent the time to go through the process of drilling a hole in the fairings.  Some people on here have done it.

For turn signals their are a bunch of aftermarket options.  I have these  http://www.motosport.com/street/product/LOCKHART-PHILLIPS-TURN-SIX-SIGNAL/?catalogId=104047&pssource=true&psreferrer=http%253A%252F%252Fwww.google.com%252Fsearch%253Fsource%257Cequalto%257Cig%257Camp%257Chl%257Cequalto%257Cen%257Camp%257Crlz%257Cequalto%257C%257Camp%257Cq%257Cequalto%257Clockhart%2Bphillips%2Bturn%2Bsignals%257Camp%257Caq%257Cequalto%257C1%257Camp%257Coq%257Cequalto%257Clockhart%2Bphilli%257Camp%257Caqi%257Cequalto%257Cg10&gclid=CP6un9Pl65sCFdVL5QodT0465Q&ef_id=1683%3A3%3As_837d6eacccdc42a99c25526a86c09511_2840444755%3ASmhS3tBkOIYAAESAxPkAAAGA%3A20090723120902&segment=badger-street

I also have led blinkers in my mirrors to make sure their is light flashing forward and to the sides since flushmounts do a poor job at letting someone in front of you see that you are turning.  In the rear i am running an integrated led taillight with blinkers but don't know much about it since it was installed by the PO.

Fenderectomy is a popular mod that helps the look of the bike.  The potential for teh bike is only limited by your creativity as for what it can look like.  Alot of people on here have really nice bikes but it is a matter of how much time and effort you are willing to spend working on it.

you can 'chop' the stalks of the signals as described in the mods section of this site. It worked really well for me, so anyone with more than half a brain should be able to pull it off beautifully