Thunar is a file manager for Linux and other Unix-like systems, written using the GTK+ 2 toolkit.

Flexible Renamer is a free tool for renaming files and folders, either singly or in large batches, including subfolders.

Rename Master is a bulk renaming software.

Ant Renamer is a free program that makes easier the renaming of lots of files and folders at once.

Flash Renamer is a mass file renaming utility.