I am not sure when ESRI published ArcExplorer, but recently I found the Mac version. This allows me to quickly interrogate ESRI shape files, ArcInfo coverages, and ArcSDE layers -- something that previously required opening my Wintel laptop. Here is a short description of this product from ESRI website:
This freely-available software offers an easy way to perform a variety of basic GIS functions, including display, query, and data retrieval applications. It can be used on its own with local data sets, or as a client to Internet data and map servers.For more information and a free download (does require registration), go to the ArcExplorer page.

