##A preview
Before I show any code, here's a preview of what is possible with some tweaking:
##First try
I don't have time to finish this, but here's a go at implementing the idea from cormullion's link.
First, let's generate the word data (this is pretty arbitrary):
punctuation = ",/.<>?;':\"()-_!&" (* boring words: *) common = {"the", "of", "and", "to", "in", "I", "that", "was", "his", "he", "it", "with", "is", "for", "as", "had", "you", "not", "be", "her", "on", "at", "by", "which", "have", "or", "from", "this", "him", "but", "all", "she", "they", "were", "my", "are", "me", "one", "their", "so", "an", "said", "them", "we", "who", "would", "been", "will", "no", "when", "there", "if", "more", "out", "up", "into", "do", "any", "your", "what", "has", "man", "could", "other", "than", "our", "some", "very", "time", "upon", "about", "may", "its", "only", "now", "like", "little", "then", "can", "should", "made", "did", "us", "such", "a", "great", "before", "must", "two", "these", "see", "know", "over", "much", "down", "after", "first", "mr", "good", "men"}; text = Select[ StringSplit@ StringReplace[ExampleData[{"Text", "AliceInWonderland"}], Alternatives @@ Characters[punctuation] -> " "], StringLength[#] > 2 & ]; text = DeleteCases[text, w_ /; MemberQ[common, ToLowerCase[w]]]; Now that we have the data, let's take a word tally and generate words at sized proportional to their frequency:
words = TakeWhile[Reverse@SortBy[Tally[text], Last], #[[2]] >= 10 &]; styledwords = Style[#1, FontSize -> #2, FontFamily -> "Times"] & @@@ words 
Let's rasterize and binarize these (the binarization is to ease overlap detection):
images = Binarize@Rasterize[#, "Image"] & /@ styledwords; This counts black pixels in an image:
count[img_] := ImageLevels[Binarize[img]][[1, 2]] Now run this:
canvas = Image[Graphics[], ImageSize -> {1000, 1000}]; Monitor[ Do[ x = 0; w = images[[i]]; cc = count[canvas]; centre = RandomReal[0.1 {-1, 1}, {2}] + {0.5, 0.5}; compose := res = ImageCompose[canvas, SetAlphaChannel[w, ColorNegate[w]], Scaled[centre + x/100 {Cos[x], Sin[x]}]]; compose; While[count[res] - cc - count[w] < 0 && x < 80, x += 1; compose; ]; canvas = res, {i, 1, Length[images]} ], canvas ] canvas // ImageCrop 
##Second try: converting all this to vector graphics
I used images but his should only be an aid for calculating positions. The images should be dilated prior to arranging them (to have more "air" between them), their positions should be recorded, and the recorded positions should be used to arrange the vector versions of words.
Here's a basic implementation:
images = ColorNegate@Dilation[ColorNegate[#], 2] & /@ images canvas = Image[Graphics[], ImageSize -> {1000, 1000}]; positions = {}; Monitor[ Do[ x = 0; w = images[[i]]; cc = count[canvas]; centre = RandomReal[0.1 {-1, 1}, {2}] + {0.5, 0.5}; compose := res = ImageCompose[canvas, SetAlphaChannel[w, ColorNegate[w]], pos = Scaled[centre + x/100 {Cos[x], Sin[x]}]]; compose; While[count[res] - cc - count[w] < 0 && x < 80, x += 1; compose; ]; canvas = res; AppendTo[positions, pos], {i, 1, Length[images]} ], canvas ] Rasterize[ Graphics[MapThread[Text, {styledwords, positions}], ImageSize -> 1000], "Image"] // ImageCrop 
There's a lot of refinement needed though (I didn't have time to tune the parameters).