- Find all files modified in the last 90 minutes  
    find . -type f -mmin -90  
  - Find all files and do something to each one
    find . -type f -mmin -90 | xargs ls -l  
  - Find all files modified before 2 days ago  
    find . -type f -mtime +2  
  - Removing files older than 7 days  
    find . -type f -mtime +7 -name '*.gz' -exec rm {} \;  
  - Find all files modified after last 2 days  
    find . -type f -mtime -2  
  - Find all files modified at the last 2 day mark  
    find . -type f -mtime 2

There needs to be a new version of find with a more intuitive UI. (I suspect it exists, but I can't remember the name right now)