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.
costar coster coaster caster castor gaster gastrea gustier keester keister keyster kiester quester questor gastraea quaestor
star costar daystar juster aster kiester gaster faster baster ristra stare astir master zester stir satara jester fester maestri stair bistre sitar keister nestor lister raster bestir shyster sistra wester waster rouster toaster taster roister diester pastor lustra laster wrester pester roster piastre oyster mister vaster quester easter pastry heister jouster vestry buster foster ouster coster ester duster bister moister keyster caster feaster boaster muster castor keester quaestor bistro nester coaster poster chaster booster waister meister piaster luster lustre rester questor paster rooster hoister royster wastry leister sister xyster roaster zoster maestro rostra diaster tester yester
costa cost costae cast caste coast coesite coset cosied cosset