I would love to get a flash, the FA 35/2 and may be the DA 15 if the price is good.
I've just bought the FA50 and I love the f1.4 but its a bit too long for indoor. I use this lens in company's Xmas party I can go without flash yet the picture is still bright. I love the speed, bokeh and its compactness but its a bit too long for indoor, so I ended up taking mostly solo portrait and no group shots. I found myself need to get at least 4-5 feet away to get a head and shoulder shot.
After the FA50 I think I am in love with the FA primes so naturally I set my eyes on the FA35/2. Hopefully I can get it within the year.
The flash, it is also related to the FA50. After using the FA50 I realize a flash can really do something a fast lens couldn't do. That is giving me big DoF while using a faster shutter speed and lower ISO. I'm still not too sure how much better I can get by buying a flash so I will start with something cheap (so the AF360 and AF540 is out of my list). Also I want to spend sometime to see if I can improve my shots without getting anything extra. So any lens/flash I will try to delay buying as much as possible.
The DA15 will probably be my "fun" lens. As the widest I have is the 18mm from the 18-250mm and the kit lens; would love to try something wider if I have the chance.
ps: if there's a "Pentax Santa", tell me where should I send my letter to