To be honest it is your pictures that have inspired me even more to invest in a 10mm lens because to be frank those canyon shots are amazing!
I will definitely need a 10mm, maybe the 50mm and the 17-55?
unfortunately the 10mm does come at a price, the canon one anyway.
I looked at both the canon and the sigma and while the sigma is a lot cheaper I kept seeing reveiws on how good the canon was a how little distortion it has at 10mm, thats what drew me to get it and i'm not disappointed. Most of the shots were taken at 10mm and i see very little distortion (not that its easy to see with random rock patterns anyway) but I also got very little when shooting with it in chicago with the buildings, you have to careful at which angle you use it though, really needs to be kept horizontal to keep distortion to a minimum.
A lot of people on here swear by the sigma too, although i have heard its very hit and miss as to whether you get a good one or not, some real dodgy ones out there too.
So its really down to your budget I guess.
As for the 17-55, its my most expensive lens because of its low light capabilities, f2.8 throughout is great, especially if you don't want to be using a big flash, until recently i hadn't even used my flash, and when i did i realised why i like to use the fast lens instead! As said though, its bloody expensive, maybe something to save up for etc as you just want to be using the kit lens to learn at the beginning seeing as it has the same range. (don't forget the kit 18-55 is VERY different to the 17-55 we are talking about here!)
As for the 50mm, i've had one for a while, used it once or twice, its a difficult lens to work i think, very little room for error but the results are stunning when you get them right, i have just got a macro filter for it so i really must use it more and give it a go, its been very much neglected, and its a stunning lens for the price!
500d sounds nice too, i have the 50d which is its big brother, but the 500d seems to have most of the features and have video too (something I think is a flash in the pan personally on these types of cameras, lots of fuss was made when the d90 came out, have we really seen anyone use it properly yet, not really!)
