If you have a specific prompt to go with a particular project, or some reason to load different prompts at different times, you can use multiple bashrc files instead of always using your ~/.bashrc file. The Bash command is something like bash --rcfile /home/giles/.bashprompt/bashrc/bashrcdan, which will start a new version of Bash in your current terminal. To use this in combination with a Window Manager menuing system, use a command like rxvt -e bash --rcfile /home/giles/.bashprompt/bashrc/bashrcdan. The exact command you use will be dependent on the syntax of your X term of choice and the location of the bashrc file you're using.