MIGX (multiItemsGridTv for modx) is a custom-tv-input-type for adding multiple items into one TV-value and a snippet for listing this items on your frontend.
It has a cofigurable grid and a configurable tabbed editor-window to add and edit items.
Each item can have multiple fields. For each field you can use another tv-input-type.
See the official documentation here: http://rtfm.modx.com/display/addon/MIGX
New in MIGX 1.2.0
Changelog for MIGX.
- merge scriptProperties to Placeholders
- basic compatibility for modx 2.2
- autoinc-field: MIGXid
- autoResourceFolders - functionality, autoCreate directory for each resource (only revo 2.1.x)
- url-TV support
- context-based basepath issues
- remove remaining 
- remove Tiny-instances when switching form
- enter on textarea closes window
- fireResourceFormChange for drag,remove,duplicate