It would be great and would look more professional if I could have access to assembla and all the tools from my own domain, such as

assembla.mysite.com

or for particular space

assembla.mysite.com/space.

Right now its assembla.com/spaces/space.

It would be much better if clients would have the impression the tool is on our site.

integration of gantt functionality would be great, even stand alone at the beginning would be of great benefit

Add codeblocks with syntax highligtning for the wiki part of the space.

To show costumers / coworkers how to use the latest addition or when discussing /planning certain pices of code.

ref somthing like this
http://code.google.com/p/syntaxhighlighter/

Add the ability to make ticket relationships across spaces under the same subscription

Ability to create and manage tickets via the new netbeans issue tracking plugin.

- select space & ticket, press START/STOP to count time for this ticket
- aplication is always present in system tray, logging to assembla is not needed for every ticket
- change status of ticket from the application
- link to the ticket in assembla

Allow to define "Access Levels" on each content instance (ticket, wiki page, milestone, etc.) created in a space, then allow to group space users and assign none/read/write/delete privileges to each group for each access level. This should be an optional additional granularity to current module level access privileges setting.

It would be very nice to have as an owner possibility of connecting team member with his $/per hour price. Paychecks would be easy as one two three. Additional feature would be setting price in a period of time for ex. Martin 01.10 - 02.12 10$/h, Martin 03.12.08 - 05.01.09 15$/h (because it's christmas time). I would be very easy to control bonus hours, in one listing.

For printing or offline review

Agile Planner is nice, but only Sprint Backlog has the burndown chart. There needs to be similar thing for release planning and product backlog burndown and team velocity.

Please provide to write RTL in all editors site.

It would be very important to have an additional custom field type for tickets allowing the selection of multiple team members.
The 'Assigned to' system field should also be of this type!
Proposal for GUI: A) either a list with multiple selections B) combo boxes - a new one appearing each time a user in the previous one has been set.

There are many ways to make UI clean and beautiful. Look at GitHub and Bitbucket interface designs and concepts, they are more usable and obvious, as Assembla user interface is.

Tickets should have a 'tags' field allowing multi-dimensional categorization and filtering. A 'tag cloud' type interface should be displayed or accessible from existing ticket list / filter views. Ideally this would display ticket counts next to each tag, and clicking on a tag would add it to the current filter (refining counts for sub-tags).

This functionality will greatly assist in dealing with large projects. With a sizable backlog, the tag interface can improve searching/navigation. The ticket counts by tag also help give visibility on common issues and can provide guidance for prioritization.

Allow for the creation of custom ticket workflows so you are not confined to the 4 current statuses (new, ready to test, fixed, and invalid) so that tickets can be adapted to any company's process.

In the Time panel ( tab ) the time reporting customization should have the option to select one or more Custom Fields for all Tickets.
In our case, each ticket has a Custom Field 'SOW' that needs to be included for a time report.

You can't get total time by user/users in milestone now. It would be very useful if the results could be grouped by milestone.