My interest in English grammar began because of learning about the rules of grammar while learning Latin. In inter-language dictionaries, it’s common to mention the declension of nouns, conjugation of verbs, etc.
In English, however, I’m often hard pressed for a source to turn to when I want to know what the past participle of a verb or the comparative of an adjective is. I frequently turn to the Oxford English Dictionary, and it is occasionally useful (there is a nice note about the comparative and superlative of little), but it doesn’t appear to be at all consistent (there is no mention of the comparative and superlative forms of stupid).
Are there better sources for this information?
My best recommendation is Wiktionary.org, which contains forms, pronunciations, even anagrams.