Microsoft seems to always have had problems building up 'app marketplaces' on their devices from Windows 8 to Windows Phone 8. Their problem is that developers haven't had any urge to immediately build apps for these operating systems because they are not the most popular in the market – Windows and Windows Phone has a tiny fraction of the market share compared to iOS and Android in both the smartphone and tablet market.
However Microsoft has decided to tackle this problem by launching a Windows 8 app in beta which allows passionate Windows 8 users to easily build apps for the platform without needing to write a line of code! This works in Microsoft's favour as it means that there will be a steady trickle of fresh apps entering the 'app marketplace'.
Once the app is downloaded and opened (link: http://apps.microsoft.com/windows/en-us/app/5ae47651-e8f3-4e41-aab7-e19ab1b80180), you are shown a two minute tutorial video and then your blank canvas is presented on your screen. You can add content via the bar on the right hand side of the screen then add excel functions and edit the functions at the bottom.
Of course "Project Siena" isn't as powerful (or as complex) as app building programs like Virtual Studio however "Project Siena" is perfect for creating catalogues, guides and information logs of all variety. Once you have finished the app you can add a splash screen, icon and publish it – for free – to the Windows 8 'app marketplace'.