Boost is recommended to help with caching in Drupal 7 for "anonymous" traffic. That's users that aren't logged in. I installed it here at PcHousekeeping a few days ago and it really seems to have picked up the speed.
The super support folks at KnownHost installed Memcached for me today on my VPS. I also asked for the PECL Memcache libraries and they got the latest stable version which is 2.2.6 at this time. Did I need it? No not for this little site with light traffic, but I had to see how it all worked so that when the time comes I will know.
One of the first things I have seen when looking at YSlow and Pingdom reports is the need to serve files that change little from a CDN (Content Delivery Network). Using the CDN module for Drupal 7 worked on one site, but here at PcHousekeeping it just wouldn't play right. I found a good tutorial by Wim Leers the developer of the CDN module and it encouraged me to use commercial CDN service.
Thanks to some helpful web searches PcHousekeeping is using Apache Solr with the Drupal Apache Solr Search Integration module. The Facet API module is also installed to give all the nice search filters. This site really doesn't need the extra power of Solr, but since so many people need help with it I needed to be able to do it.
The AvantLinker module for Drupal 7 has been listed today at AvantLink as a Certified 3rd Party Affiliate Tool. This duplicates the functionality found in the plugin that they developed for WordPress. It automates a lot of your affiliate link building activities.