Minimalist Markdown Editor - This is the simplest and slickest Markdown editor.
Aspose.Slides for Cloud - Use cURL commands to create, manipulate, merge, split & convert PPT PPTX presentations & slides to PDF, XPS, TIFF, ODP, OTP, HTML & other formats.
Typora - A minimal Markdown reading & writing app.
GitPitch - The Markdown Presentation Service on Git
Markdown by DaringFireball - Text-to-HTML conversion tool/syntax for web writers, by John Gruber
PPTX Viewer - PPTX Viewer is one of the lightweight applications that allows you to view, create, edit and share your presentation without facing any advertisement issue.