LetsExtract Email Studio allows you to extract email addresses, and unlike free online services, works much more accurately and offers rich customization options.
You can also use this feature to import contacts from other programs.
Currently the following file formats are supported: CSV, TXT, HTML.
Now the program also supports document formats: Adobe PDF, Microsoft Word(RTF, Doc, Docx), Microsoft Excel (XLS, XLSX), PowerPoint (PPT), OpenOffice (ODT, ODX, etc).
See also: how to verify email addresses, mass mailing software.