Hide development of blog

Quick question for anyone that can help …
While creating my blog in WordPress (and using a theme) I obviously want to hack it up and play around and upload some stuff, see how it looks, change images etc- but I dont want any of it to be showing LIVE on the URL – which it currently does. Is there anyway in WordPress to set the site to “invisible” for all users who may stumble on my URL – but I, the admin – can see the development in progress? Thanks!