With vimwiki plugin it's simple to maintain wiki-like knowledge base or diary. It allows you to organize notes and ideas, manage todo-lists, write documentation and more.
Ranked in these QuestionsQuestion Ranking
Pro Internal link makes it easy to create a knowledge network
Pro Comfortable for Vim users
Has a very minimal learning curve for people already used to Vim, as the preset shortcuts are very easy to learn and don't conflict badly with other Vim behaviors.
Con Limited to use with vim only
vimwiki is a plugin for vim, so you won't be able to make use of it if you're not a vim user (and don't want to be).