From Wikimedia Incubator
Export & import 
What i wanna do in particular for export:
- regex for pages to export (bug 3760), or at least "pages starting with ..."
- replace occurences of X with Y in the to-export-pages
What i wanna do in particular for import:
- Update statistics tables (bug 5703)
Language support 
- Language name cache (there is currently a performance issue when using xyz a lot of times)
- Default list of (English) languages
If time permits
- Intuitive language picker: instead of a list sorted by langcode, a inputbox with suggestions (easy, but it needs to be good)
- Ability to specify a per-page language: a per-revision language passed to getPageLanguage, either core or extension. With a language selector in the edit page to change it.