There are several different feedback channels. In decreasing order of preference, they are:

Read the instructions to report bugs. 

The Android Studio User Experience team is looking for Android developers who are interested in providing feedback on new and existing features and helping to inform our priorities. If you are interested in being a part of upcoming studies, you can sign up here.

Write to our forum, http://groups.google.com/group/adt-dev. Please use the new forum adt-dev in place of the android-contrib one.
Please note that this is not a user support forum. This forum is for people working on Android and tools. It is heavily moderated and user support questions will not go through.

For user groups and other community related lists see http://source.android.com/source/community.html .

If you have other ideas, related to tools only, but you don't want to file a bug or write to the forum, you can send an e-mail to the following alias:

   tools <at> a n d r o i d <dot> c o m (no space)

Please consider using one of the other feedback mechanisms before writing to the feedback alias. We appreciate any and all feedback we can get, but we may not respond to direct e-mails. 

NOTE: THE ABOVE E-MAIL ALIAS IS ONLY FOR FEEDBACK ON THE DEVELOPMENT TOOLS, NOT GENERAL ANDROID FEEDBACK!