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.
lumpy lump lamp limp limpa
humpy dumpy lumpy jumpy bumpy ump rump champy hump whump hempy sump jump pump bump gimpy jimpy mump dump vampy tump lump mopy wimpy campy chump
lum louma luma alum blume flume glum glume plum plumb plume plummy plumy slum slummy