Download Manager allows you to save any email attachment or downloaded file, even formats that your email client and web browser normally can't handle, such as Microsoft Word and Excel documents, APK, RAR, ZIP, PDF, MP3, DOC, XLS, and other file types.
Download Manager acts similarly to a browser or email plugin and allows you to save files and attachments directly to your device's SD card.
This is compatible with your built in web browser, email client, and GMail.
Note that Download Manager does not allow you to save streaming video from sites like YouTube due to Google policies.
This is a free ad-supported utility.