Report Headers / Titles

You betcha. 

Just of to the report (can't do this from your default report or non your home page) and click on each header you would like to rename. You will see two options at the the bottom, one for 'Column properties' and one for 'Field properties'. Click on 'Column properties'.

This will give you the Column heading override settings. Give that column a good heading (justify it if you wish) and click 'OK'.

Now, this is IMPORTANT, you will see a small grey box at the top of the report with a blue button that says "You've made changes". YOU MUST CLICK SAVE or it will not save the column override. 

This override is per report and does not make the column header change globally.