FSQL is the tool I use approximately one year instead of standard ISQL.
It has some enhancements, like commands to import data from csv,
show attached users, inserting file contents into blob, etc.
To list new commands execute HELP command, short description,
some examples, and link for download is here:

http://www.volny.cz/iprenosil/interbase/

Any feedback is welcome.

Ivan Prenosil