TortoiseSVN Password Decrypter is a free utility that can view cached repository credentials that TortoiseSVN has saved on your PC.
This handy little tool is helpful if you have check-marked the 'Save authentication' box at some point in the past, but have now forgotten the password you had entered.
TortoiseSVN Password Decrypter stores your cached credentials inside files in the %APPDATA%Subversionuthsvn.simple directory. These passwords are encrypted using the Windows Data Protection API, with a key tied to your user account. TortoiseSVN Password Decrypter is able to read the files and uses the API to decrypt your passwords.
TortoiseSVN Password Decrypter can be run from a script; you can specify the -s switch to avoid the "Press any key" prompt on completion.