No, you can't put wildcards in your PATH. A common practice is to create a directory named $HOME/bin (where $HOME is your home directory) and put your own programs in there. The HOME environment variable is set up for you automatically by bash when you log in. It's also a common practice to let programs in your current directory be run, by putting "." in your PATH.
In your .bash_profile, therefore, you would put a line such as:
to add your private "bin" directory and your current directory to the end of your PATH. Note that the order of directories in PATH is important, so if you want your own programs to be used in the unlikely case that they have the same name as a system program, put your directories first.
Finally, if you have programs scattered around many sub-directories, and you don't want to move them to your "bin" directory (perhaps you update and recompile them frequently), then the thing to do is create a symbolic link from your "bin" directory to the program using "ln -s". For example, if you have a program at the pathname ~/projects/src/driller/drill, the command:
ln -s ~/projects/src/driller/drill ~/bin
will create a link to that program in your "bin" directory, and it will thus be found when the shell searches your PATH.