The export back-ends in Org often include commands to convert selected regions. A convenient feature of this in-place conversion is that the exported output replaces the original source. Here are such functions:
org-ascii-convert-region-to-ascii ¶Convert the selected region into ASCII.
org-ascii-convert-region-to-utf8 ¶Convert the selected region into UTF-8.
org-html-convert-region-to-html ¶Convert the selected region into HTML.
org-latex-convert-region-to-latex ¶Convert the selected region into LaTeX.
org-texinfo-convert-region-to-texinfo ¶Convert the selected region into Texinfo.
org-md-convert-region-to-md ¶Convert the selected region into Markdown.
In-place conversions are particularly handy for quick conversion of tables and lists in foreign buffers. For example, in an HTML buffer, write a list in Org syntax, select it, and convert it to HTML with M-x org-html-convert-region-to-html.