Firstly... Re: the joke...
far-fetched
Secondly... Chris... Bit of a random question that bud! Just for my amaturish 2 cents' worth though... I guess it depends largely on what you want to photograph... Key things to consider though - what focal length you do want/need? Once you've decided that you've got a starting point... Next you'll want to consider things like the widest aperture you're after (or in reality, wish to spend on), or perhaps whether you need things like image stabilisation or not...
The kit lens isn't a bad bit of glass, depending on what you want to do with it (imho)... The optics are pretty good, it's just that it has an 'average' field of use and in some situations it'd be nicer if it went down another aperture stop or two...
If you want to do sports or low-light photography you'll need to be looking at something that is perhaps f/2.8 or lower and maybe even has image stabilisation (which it is argued can effectively drop another f/stop). If you need range with this, I'd be looking at 300mm type stuff - but then to get a 300mm f/2.8 (perhaps with IS) you're looking at a lot of money (upwards of five times the price of the body!)... For general use I have the 18-55 kit lens and a Sigma 70-300 APO DG - the Sigma isn't an awe-inspiring lens, but used properly it's not bad, and certainly worth the ~£130 it sets you back. A decent f/2.8 glass would knock spots off it though.
If you want to do serious landscapes perhaps, you need to be looking at wide-angle (or perhaps fish-eye if you like the effect). Sigma do a 10-20mm and its widely regarded as a brilliant landscape lens. That'll probably set you back just under £250 - one's on my shopping list for the not too distant future. That lens could also be quite useful for some aspects of portraiture, which is another reason why I fancy one - I've got studio flashes to buy first though!
So... I guess... What do you want the lens to do bud?
Regards,
Rob.
PS> Maybe we should take this over to the Photography forum...
