Create virtual corpora that are based on keywords or topics or metadata (such as date or author or publication). And then find keywords for these virtual corpora, or limit future searches to that virtual corpus.

Save words or phrases that appear in the results of a search, and group these by topic (e.g. science or sports). Particularly useful for language learners.

Create your own word lists for any topic, such as colors or clothing, and then re-use these lists as part of a search (for example, @colors @clothes).

Save the entries from KWIC (Keyword in Context) / concordance lines, and move entries from one list to another.