Treemaps of journal titles and MeSH headings of the most recent papers added to MEDLINE. Not sure how useful these are yet, as they don't take into account the frequency of journal titles/MeSH headings in the whole MEDLINE corpus. Also, because SVG doesn't do text wrapping, the size of the text is scaled to fit into the boxes, so text size isn't representative of frequency, which can be misleading.
Made using Pierre Lindenbaum's PHP translation of HCIL's Java treemap algorithm.