Currently, to find the numerical location of a guide on the ruler, the guide has to be moved for the number of unites (i.e. 12.20 Centimetres) to be displayed. Using guides and the rulers would be much more user friendly if the position of the guide was displayed when hovering the mouse over the buide position on the ruler as shown below.
Also, the ability to right-click the ruler and enter a value for the location of a new guide would be a plus.