I've taken a list of English words, and examined each of them to see what they sound like (using the PHP metaphone function). This page lists the most common metaphone codes, along with their words. You can also search for a word of your own, and see which words sound similar - and which ones rhyme, and which ones alliterate.
grouter groutier garotter garroter grottier garter grater greater gritter courter grodier greeter grittier courtier carrotier carter grader cruder crater curter krater gridder quarter guarder crowder critter cowriter cruddier greedier criteria quartier carder corder creator crittur curator curdier
grouter router charioteer trotter prouder parroter reutter rioter rooter rootier rotter bruiter fruiter hurter carrotier courter curter garotter garroter groutier porter sorter troutier shorter
grout grouty grot croute garote garotte griot groat grotto grotty