New Oracle Database Command Line Interface from ManQuantTech
ahl.com
ahl.com
See also "rlwrap", which is a very useful tool for enhancing those command line tools which lack readline support.
Not to steal the thunder of the guys behind the orignal post, but Google for "rlwrap sqlplus" to get an idea of how quickly useful it is.
Actually, okcli started off as rlwrap with a complicated login file that queried the schema. But if you do that you can't use add a lexer for context-aware auto-complete which was one of the main goals, hence a new cli-tool using cx-oracle which gives way more control.
disclaimer: I'm the author.