With the Ultimate Under Construction plugin you are able to turn on a holding page for all non-admin users that visit your website. This holding page will allow you to work on your WordPress website on a live server without worrying about the impacts it may have.
This Under Construction plugin allows for many levels of customisation, with millions of solid background colours to choose from, Patterned background and even a region to allow more advanced users to enter a completely custom block of HTML complete with styling there really are no limitations to what you can create.
Screenshots
This is an example of what the holding page can look like, this is using the Darkbind patterned background
This is the top half of the options page, this shows the bulk of the options
This is the bottom half of the options page, here you can see the colour selector for the Solid Background option.