FBReader will handle single-file HTML and TXT. It will also handle many languages, but you may need to select a font that supports your language. On the iLiad I usually use DejaVu Sans (see crossed-tools icon, styles tab). Or convert them off-line (e.g. under Windows using MobiPocket Reader or Creator) to MOBI format. However, the DR MOBI reader probably has less language support than FBReader.