In SQL*Plus you can use the COLUMN directive to specify formatting on a per-column basis, separate from the query itself. That way you keep your query "clean" for possible other uses and still get your formatting. (In SQL*Plus at least...)
e.g
COLUMN SAL FORMAT 99,990.99
Google for "SQL*Plus User's Guide and Reference" and you should get links to the Oracle location for your Oracle version. 10.1 is here if that'll do. They'll probably all be about the same, mind you: I don't think SQL*Plus has changed much since I learned it in 1988 on Oracle 5.1.17...