Simply brilliant IDoc transactions:
WE09 / WE02 IDoc lists according to content.
WE05 View IDocs.
WE19 EDI test tool. Use to test inbound Function module changes.
WE20 Partner profile configuration.
WE30 Create/Display IDoc type and extension
WE31 Create Segments
WE57 Assign function module to logical message and IDoc type
WE60 IDoc type documentation tool
WE82 Link Release detail to Extension IDoc Type
BD55 Conversion rule user exit. Link conversion rule user exit to the different system partner combinations
BD87 Reprocess IDocs in error or waiting for action. (Use BD88 in release prior to 4.6)
BALA ALE Application Distribution
BALM ALE Master Data Distribution
Very few people know this next one and it is one of my favorites: