When it comes to finding an Android app that does something simple, you want it to be quick, easy to use and not have too many bells and whistles. This is especially true for apps that provide your current altitude.
Fortunately, I stumbled on the eGPS Altitude app. The app has a clean interface and quickly provides the altitude data I need. Just tap the globe icon in the lower-left corner and it will provide the altitude that the GPS reads as well as the altitude based on your longitude and latitude.
Oh and bonus! The app is free to download from the Android Market.