How about the Kapco clear adhesive? See, www.shadesofpaper.com
Very unique adhesive clear vinyl media. http://www.shadesofpaper.com/index.php?cPath=90&osCsid=b99jvu99g83omb9bf04svhal85
Pretty much anything for typical signage using a pigmented ink printer should be considered "temporary" but I like that there are now pigmented ink options at least to consider. I've profiled this media for an Epson 9800 and it prints well. Haven't had time to generate a profile for the 9900. Solvent printers offer more (better) solutions.