Over the course of the past 3-4 years, I have been using spreadsheets (mainly Excel) for many things ranging from homework to personal tasks to research projects. At first, I could only use it to store data-sets and some basic highlighting and charts. Then I started to work with functions and basic analysis of data as my studies required me to do so. Moreover, report generation, large-scale calculations on data-sets, some statistical analysis and finally, basic homework tasks (yes! homework, and it helped a lot!) came into play. There are many other usages to spreadsheets though; For example, project/time management.
All of these things can be done by using a specialized program (for example, R for statistics) but the thing is, when you have to do something quickly and write/generate reports the same time, nothing beats the ease of using a spreadsheet. I agree that if I get skilled in R, I can do far more advanced statistical analysis but working with specialized software needs much more learning time.
Bottom line, if Excel has the functionality that I need for a specific task, there is no doubt I will stick to Excel and nothing else (maybe just a word processor if I need to write an article for it as well).

What are your thoughts on the matter of spreadsheets? Do you use them at all?