This is the only way I can see doing it. To remove dups, highlight your column and use the 'Remove Duplicates' function in the Data ribbon.Do you want a static list or dynamic? If static, just copy and paste the values from each of the 60 columns into a single column, resulting in one column with about 3000 rows. Then, if you want to remove the duplicates, you can highlight the column, click on the Data menu and then use the Remove Duplicates function.
If you want a dynamic list and you don't mind duplicates, you can create a column that has as its first 500 rows a reference to the same cell in column A. So for the first row, it'd be =A1, the second row would be =A2, etc. down to =A500. Then, for row 501, you put =B1, do the same as for the A values, and repeat for all 60 columns.
Otherwise, you'd need to write a macro.