I have a cloth that is much like the one you get with an iPhone to just wipe any threads or dust that will randomly appear. To clean the screen and wipe the case down, I use a microfiber cloth with this solution made specifically for laptop screens... I don't remember the name and can't look it up atm because my brother took it to college with him...
I'm a fan of Mr. Clean Magic Eraser. Worked wonders on my macbook, left it white like new, and it works very well on both the mbp's surface and screen.
You are pretty mad if you are using iKlear at £10 a bottle to clean your glass screened iMac. Use Windolene, thats what it was made for, to clean glass.
iKlear may do a good job but they can spin on it if they think they can charge that kind of money for something that cost pennies to make.
I use iKlear on mine, my MacBook Pro looks like it did the day I unboxed it! I'd highly recommend it to anyone who is looking to maintain their Apple products.
High quality Kleenex or Puffs (lotion-free, of course!!) I use two....I wet the 1st with water, wipe off screen. Then use 2nd to dry. Then I use them to wipe keys & trackpad area. Perfectamundo. Cheap. Works. Never a scratch.