We accidentally missed the release of Uncomplex’s Mailplane 2.5 a few weeks ago, which gives the Gmail-specific email client support for full-screen mode in Mac OS X 10.7 Lion, along with support for the new Preview Pane feature from Gmail Labs. Otherwise, the Mailplane 2.5 release fixed bugs relating to Boomerang and Rapportive, addressed some Lion-specific bugs, and automatically adds the Evernote toolbar button when the Evernote application is installed. The just-released Mailplane 2.5.1 adds a Window > Enter Full Screen menu item and keyboard shortcut for Lion users, removes the conflicting keyboard shortcut from Mail > Forward, and fixes some problems with sending messages, uploading attachments, and two-finger swipes in Lion. ($24.95 new, free update, 22.5 MB)
Option-Click in Scroll Bars for Jump Scrolling
In Mac OS X in general, and thus in most native Mac OS X applications, hold down the Option key and click anywhere in a window's scroll bar to jump to that spot (rather than scrolling one screen). If you like this behavior, you can make it the default in the Appearance preference pane. For "Click in the scroll bar to:" select "Jump to here."