Art Kagel Utilities are used, well virtually everywhere. Not much more can be said really, if you are not using his dostats program for maintaining your statistics then you are probably not maintaining your statistics correctly.
SQLCMD [readme] is a dbaccess replacement written by Jonathan Leffler, can be downloaded from here
Squirrel SQL Client Client is a graphical Java program that will allow you to view the structure of a JDBC compliant database, browse the data in tables, issue SQL commands etc