Much depends,of course,on what car you have. Whatever dock you decide on (and I have a few suggestions below)I'd recommend a Brodit fixing kit. They have clips for just about every make and model of car, often to fit in several different positions in the car so you can choose which one suits you best. The other great thing about them is that they all fit without any screws so you can remove them without any damage to your car. They also do passive or powered docks.

Link is

http://www.dsldevelopments.com/?gclid=CJPWgrvE558CFcIB4wod9nyBGg

I've got nothing to do with either company, just a satisfied user over several cars, honest.

To get the sound out and into your car, I've tried loads of these but the one I have always struggled to better is the Belkin Auto kit. This fits inside a Brodit mount if you want to, powers/charges and has line out (as long as you have a line in, of course). Only problem with this is that it doesn't charge an iPhone without a hack

The best FM dock I've used is the Macally Cup FM - sits in a coffee holder and has the strongest FM signal I've come across - I never found a station that interfered with it, and I used to drive all over the country, all the time. I must have tried half a dozen others but nothings ever come close.

Final option I have if you don't have a line in is to get an FM modulator fitted. They're not expensive and a car audio specialist should charge more than £30/40 for doing this (although fitting it yourself isn't too hard). Much better than a transmitter.

Warning, this will become an obsession (can't you tell from my ramblings ?)

That's really helpful. That should fill my day.

The simplest way is to make sure that you start off with a Head Unit that has a bit of flexibility. I'm fortunate to have a Blaupunkt unit that has two auxillary connections on the back. I just bought a lead (the proper Blaupunkt one was only about a fiver) and I plugged one end into the back of the radio and the other into the headphone socket of my ipod. If I need to charge the pod I can still do that from the lighter socket. I rarely tough my ipod when I'm driving so donn't feel the need for a cradle.

works really well. I use it more for for my iPod than I do for the radio. Not the cheapest solution, but if you fancy DAB as well, worth a look.

and comparatively cheap one made by (I think) Gear 4. However, if I had a car and the need for a new one, I'd probably go for the Pure one

I've decided to go for the Pure.