Commons comes with some blocks that guide you towards new content through "most active" groups and newly posted groups. However, these algorithms are not useful for installations with a lot of content. The two items that would greatly improve knowledge management are trending posts and recommended content. There some existing solutions and technologies that could be leveraged to provide simple but useful suggestions that would help cut through the fluff in larger document sets.
In any community it is important to show the trending / most popular content. The Radioactivity module provides a lot of options that helping this area. This isn't revolutionary stuff, just wanted to get the idea down.
Although there are next-gen recommendation engines such as Apache Mahout, it would be a low level of effort to tie in the benefits of Solr to provide personalized results and recommended content via the MoreLikeThis capability of Solr. We have some data points such as User Terms and the "My interests" area that could be used to boost certain documents in the search results and perform the MoreLikeThis queries.