words <- readLines("http://wiki.puzzlers.org/pub/wordlists/unixdict.txt")
word_group <- sapply(
    strsplit(words, split=""), 
    function(x) paste(sort(x), collapse="") 
)

counts <- tapply(words, word_group, length) 
anagrams <- tapply(words, word_group, paste, collapse=", ") 


table(counts)
counts
    1     2     3     4     5 
22263  1111   155    31     6 

anagrams[counts == max(counts)]
                               abel                               acert 
     "abel, able, bale, bela, elba" "caret, carte, cater, crate, trace" 
                              aegln                               aeglr 
"angel, angle, galen, glean, lange" "alger, glare, lager, large, regal" 
                               aeln                                eilv 
     "elan, lane, lean, lena, neal"      "evil, levi, live, veil, vile"