Portable version of the excellent dual-pane file manager discussed in the Desktop Application section.
7-Zip File Archiver
IZArc Archive Utility
PeaZip Archive and File Manager
As file archivers, all three are very workmanlike. For secure files, IZArc and PeaZip are the easiest to use for creating encrypted zip files with password protection. 7-Zip can do it, but only with command line (read DOS) switches. If you are not careful during installation, PeaZip will hog all archive file type associations even if you do not want it to. On balance, therefore, I prefer IZArc.