This is a set of Krusader useractions which will convert various document formats to plain text.

Supported types: RTF, PDF, LIT, PDB, DOC, HTML.

No dialog box will appear. It will simply append .txt to the end and place it in the current working directory (except for .lit files, which will create ./temp and extract all the components of the lit file there.)

The following must be installed for it to work:
unrtf
xpdf-utils
#?*@
txt2pdbdoc
catdoc

To install, open krusader > useractions > manage user actions > import. Select the downloaded file.