+1 to all of these suggestions:
Threaded SMS.
The ability to secure select applications without locking the entire device.
A free, normal Adobe PDF reader.
An app/utility that would reclaim the memory capacity lost through memory leaks.
Phone Profile - GPS Integration.
Phone call recorder.
Suretype on the full BB keyboard.
Ability to make trackball blink.
Also, I'd like the following:
Ability to click on a contact and see all my communication with that person, starting with the most recent. Calls, emails, texts, everything.
Ability to add or transfer an item from Email to Calendar to Task list to Note. Eg. I have an email and I click menu > send to > and I can choose from Calendar, Task List, Note. And it takes me to the other app, creates a new item with the same subject and body, and I fill in the details (unless it's a note) and hit save. Or from the Calendar I can email an appointment to my husband or my office calendar. You get the idea.
Ability to flag any item, and then the ability to see all flagged items with one shortcut. (Kind of a "Next Actions" list.) Or perhaps all flagged items will automatically show up in the task list until un-flagged e.g. "Flagged: yadayada".
Contact control. If I only want to hear from certain people at certain times of day, I want to be able to tell the BB to send all calls to voicemail, hide all messages and defer alerts regarding that person until a certain time of day, so I can make sure I have a drink first or whatever.
Native template creation/support for email, appointments, tasks, and text messages.
Option to automatically send all unrecognized calls straight to voicemail.
Native support for video playlists.
Ability for video player to run in the background. If I want to respond to a message while watching a video, I can't minimize it and keep listening while I work. I want to be able to do this.
Ruby Slippers app that I can click three times in the afternoon and it will teleport me home. Rush hour sucks.