Be carefull with using <bt>. The mob targetted with <bt> can sometimes be the link your RDM, BRD or BLM just slepted!
Also, /item works in trades as well.
/item "item" <t> is usefull for trading single items to an npc in front of you. (Cornettes and Boyahda Moss in particular)
/targetnpc
/item "Cornette" <t>
Another very usefull ones:
/item "Iron Ore" <st>
Running around a high danger zone, trying to get your coffer before the THFs do? (prepatch)
CTRL-1
/target <st>
/ma Barfire <me>
/wait 1
/item "Ozt. Coffer Key" <lastst>
CTRL-2
/ja Chainspell <me>
/wait 1
/ma "Warp" <me>
/say SUCKERS!
(this was my actual macro setup for Oztroja, saw 2 THFs putting on Silent Oil, so I ran past them (Sneak and Invis), jumped into the leech pool, grabbed my RDM AF, and warped out ^_^)