1. automised process for plugin and core updates.
2. pagehandler hijack being fully integrated as a core feature.
3. ajax updates for as much as possible - primarily horizontal navigation tab changes on list pages.
4. expansion and upgrading of layouts of tidypics.
5. browser extensions for notifications - as with the chromium extension for facebook.
6. integration of the elgg community_groups plugin features into core - e.g. grouping of groups (mainly).
7. connection of 'embed' to 'tidypics' and 'videolilst' to allow image and video embeds directly.
8. bottom_bar chat enhanced to include custom sounds to be added via admin for different events.
9. the smileys plugin to be coded to function on all areas of the site.
10. discussions to be enhanced so that the features and layout are comparible to other successful forum designs (e.g. view counts - stickys - thread subscription options)
11. widgets for tidypics photos and videolist videos to be coded to support 1.8 widget structure (so they appear as standard in groups and homepage_cms etc).
12. a way to restrict features only to admins, such as assigning categories to new items or uploading files to the file plugin. this would be an admin page that lists all the actions that are used in the site and checkboxes to enable them for different user types. i haven't used any 'roles' plugins so maybe this already exists?
13. add a selector to the activity stream to filter the list to only display items in specific groups. (so you can choose a specific group and view the activity for it).

14. add a selector similar to idea #13 to all entity listing pages to allow groups to be chosen, so only items for that group are shown.

15. updating of tidypics and videolist to be more integrated into the 1.8 elgg way of listing and showing entities.

16. search results page (tags view) -> adapted to show images and other entity listing types rather than an undetailed view.
17. integration of a nice image viewer into tidypics... like 'wowslider' or this 3d version: http://tympanus.net/Development/Slicebox/index4.html

some of these i can code and some are much better left to those who are already supporting the plugins.. i posted here to inform the cosmos. :)