It would be nice if search was able to look at things like the title, description, caption of images that were uploaded. For image centric blogs, you can have literally hundreds of pages of content that can't be found via WordPress search.
This could really go for all uploads, comments etc. And make an option in the admin to select which things should be in the search index:
- Posts (default)
- Uploaded Assets (default)
- Comments (unchecked by default.