Lightside Apps has just released an App on the Appexchange that allows this. 'Power Tools' is a collection of useful tools for Salesforce Admins and Developers and includes a 'Script Library' tool.
The Script Library Tool will allow you to save your apex scripts within a Script record and run them whenever you like, at a nominated time or at a schedule of your choosing. You can also view and optionally store the debug results of the scripts and best of all, no Test Classes are required.
For more information on the Script Library (and the other components), please have a look at the documentation on our website here: http://www.lightsideapps.com/documentation/scripts/index.html
You can download the App with a free 30 day trial on the App Exchange here: https://appexchange.salesforce.com/listingDetail?listingId=a0N3A00000EFoy9UAD