When you're going about your day, it's not always just your bicycle that needs to be occasionally locked up. If you were studying at the library and came back from the bathroom to find your backpack missing, you'd be just as upset. So while incredibly compact Safe+ Microlock probably isn't ideal for your bike, it should be more than adequate for everything else.
In lieu of a key that's easy to lose (and possibly pick) the Safe+ features a two-digit combination lock that's easy to remember. It of course also means it wouldn't take someone too long to guess the code, but the Safe+ is designed to serve more as a deterrent to someone looking to just quickly snatch and grab your gear.
The concept of a compact cable lock of course isn't new, but this version is touted as being the world's smallest making it painless to always have on hand. And if for just £10.70 (plus £5 shipping) it ensures your backpack/pram/suitcase remains exactly where you left it, it could be £16 very well spent. [Unikia]