While trolling the intarwebs for information to better understand the French Subjunctive mood, I came across this little gem in Wikipedia:
The optative mood was formed with a suffix *-ieh or *-ih (with a laryngeal). The optative used the clitic set of secondary personal inflections. The optative was used to express wishes or hopes.
In simpler terms this means that it is a feature of Indo-European languages (including English and even Queenslander) to add a sound something like 'eh' to the end of sentences which describe emotions, possibilities, judgements, wishes and statements contrary to fact.
Pretty cool. eh?