* Correct spelling, grammar, and capitalization errors
* Where spelling "errors" are legitimate "slang terms", link to the definition pages for those slang terms (gonna, wanna, ain't, dat's, etc.)
* Remove unnecessary extra punctuation, e.g. example sentences ending in "???" or "!!!"
* Checked keywords on top landing pages for searches like "slang", "slang dictionary", "slang thesaurus"
* Remove unnecessary extra spaces in the middle of sentences
* Use complete sentences even where completely unnecessary
* Restructure entire /definition+of/word+goes+here directory structure to be /meaning-of/word-goes-here, since people search for "meaning of" more frequently than "definition of", and since Google seems to have stopped treating + as a word separator in some cases.
* Reworked meta descriptions and page titles
* Removed meta keywords. I know Google doesn't use them, but maybe they treat them as a negative indicator of site quality? Who knows?
* Completely re-designed site's front page
* Switched from Google Custom Search Engine to a custom search implementation, because I think I can provide better results, improve the user experience, and reduce search exit rate
* Delay-load Twitter widget to reduce page load time
* Use rel="canonical" on every page on the site, since Google is indexing the IP address of the site and showing it separately in SERPs
* Removed <priority> nodes from the sitemap, just in case Google knows better
* Fixed the "HTML suggestions" on GWT, such as short meta descriptions and duplicate meta descriptions
* Excluded directories via robots.txt like /word-of-the-day/, since the words of the day are already spidered elsewhere on the site, in case Google is giving me a duplicate content penalty of some kind
I've also made plenty more changes in the past month, but I haven't written up a list yet.
Sine the Panda update, I've seen no improvement in traffic from Google to my site.