Well, I went for those semi ridgid panniers. The response on them seems to be a bit mixed, but I think they are pretty good. Adds a bit of practicality and I think they suit the bike.
I also got the high screen, which was a total waste of money. Took it off as soon as I got home and it's never been back on.
I had Oxford heated grips fitted. Essential for non-summer riding. Those hand guards don't really keep the wind off your hands.
About 6 months after I bought the bike, I got the Akra exhaust fitted. Bike has a voice now. Expensive, but I love it.
I picked up a comfort seat off ebay. It looks better on the bike, but not sure it improves on comfort.
I've also got a low seat. I didn't need it, but again got it a bit cheaper than RRP off ebay so my short-arse mate could have a go. Does seem to lower things a fair bit.
I also thought about the fog lights, but the price seems a lot for a couple of torches, a bracket and a switch.
Don't think the bike needs them. The LED headlights are brilliant.
Wasn't really anything else that I felt I needed.