This odd, slightly kinky accessory actually does a couple of useful things.
First and most importantly, the Belkin Laptop CoolStrip elevates your laptop a little off the desk to let the air circulate more freely under it.
The fans in your laptop are only so good at pulling air across the components in your Mac that generate heat, and they need all the help they can get, both by ensuring the air intakes aren't blocked – as they might be if you were using your laptop on a soft bed – and by letting heat radiate away passively.
By lifting the rear of the laptop, you're helping both, though even with temperature monitoring utilities, the difference can be difficult to see.
The rubbery stalagmites also give you an opportunity to thread cables underneath. It's perhaps not as appropriate to Apple's modern laptops as to PCs – MacBooks and others have their ports on the side, not the back – but it's handy.
The Belkin Laptop CoolStrip is available in grey and the 'ice' colour you see here.