DroidEdit is a text and source code editor (similar to Notepad++ or gedit) for android tablets and phones with the
Lua, LaTeX, SQL, ...), Several color themes, Infinite undo & redo, Search & replace, Auto & block
indentation, Keep opened files and changes between sessions, Open files directly from dropbox or a file manager,
Character encoding support, Configurable Keyboard shortcuts, Share documents with other services (dropbox, email, ...),
Preview HTML files in browser, Bracket matching, Go to line and Run Scripts in SL4A directly.
The Pro version also has: SFTP/FTP support, Dropbox support, Custom themes, Run external commands through SSH and Root mode
Try Hacker's Keyboard for a developer friendly virtual keyboard.
You should try the ad supported DroidEdit Free before buying this app. The ad supported version has exactly the same functionality as the paid version except it doesn't have SFTP support, Dropbox support, Custom themes and Root mode.