SlickEdit's Defs Tab gives you a powerful overview of the currrent file, showing all the tags and attributes in a file and highlights the tag that the cursor is currently in. Double clicking an item will take you there immediately. List items alphabetically or by line number.
For XHTML this tab includes XPath searches and the ability to add and delete attributes.
See more cool tagging related features here.
FTP Open Tab
SlickEdit's FTP Open Tab allows you to open a file directly from an FTP site. Saving the file will save the file locally and prompt to upload it.
This can be much more convenient than using a traditional FTP client.
SlickEdit's FTP Open tab is a very convenient way to open files, but sometimes you just need to transfer files.
This is why SlickEdit also has an FTP Client so you do not have to leave and go to another application to transfer files.
Typing "</" in SlickEdit will automatically close the open item, and indent the closing tag properly.
SlickEdit's XHTML Validator tells you where the problems in your XHTML code are.
Automatically formats line selections when pasted. The pasted code is formatted to match the indentation of the new location and the brace style adjusted to match your settings. This also starts Dynamic Surround.
When you press Enter in SlickEdit, the cursor does not just go to the beginning of the line. It goes where it belongs. This works even for complicated statements.