Not only can you copy an email address from Contacts and paste it into the To field, but you can also select multiple contact items and insert them into the body of email.
How to launch:
1) Touch and hold the mode key (Note 1) of the keyboard to display the menu.
2) Tap the extension icon (Note 2) to display the extension list.
3) Tap Contact Picker 2.3.
Note 1: Bottom left key for switching between Kana mode and Alphabet mode
Note 2: Puzzle piece icon
For Android 1.6 and Android 2.1, use ""Contact Picker"" and ""Contact Picker 2.1"" respectively.