One job that I've found to be a PITA on modern cars is cleaning the inside of the front / rear windscreens. The rear, in particular, is virtually impossible to reach by hand, and you really need to be a contortionist. So, I came across this very useful tool produced by Invisble Glass which makes the job much simpler. It works well with just a light spray of water to dampen the micro-fibre mop head, it easily reaches all parts of the screen incl. corners, and leaves a streak-free finish. If the glass is more soiled I just spray on some AG Fast Glass instead of water.
It comes with 3 different mopheads. It's not that cheap at £16.99, and I'm sure there are cheaper tools, but it works so well that it's money well spent IMO. I've had to order a second one for the car as my wife has nicked the first one for doing the house windows.