This form will import your GPS data file (e.g., GPX), or plain-text data (tab-delimited or CSV), and create a KML file that you can view in the Google Earth application or import into Google's "My Maps"/"My Places" system.
(You might also be interested in the Google Maps input form, which can create an interactive map that can be viewed in almost any Web browser; you can even use KML/KMZ files as input. For SVG or JPEG maps, use the "classic" map form. To resize and/or colorize Google Earth markers based on a particular field, use the data form.)
NEW: If you want to add altitude information to your KML file, enable the option labeled "Add DEM elevation data." GPS Visualizer's server hosts a 90GB database of digital elevation data that can be integrated into your data.