If you work in the finance domain you are often confronted with data in spreadsheets. I've used a number of ways to read spreadsheets before like Scriptom (Groovy) or POM (Java). Ruby comes with a windows specific OLE bridge which allows you to use COM to communicate with a number of different MS applications. The pickaxe has more details.
Here is a 4 line working example of opening an Excel document, choosing a worksheet then printing the values of a range: