The best replacement for sharepoint is wiki.

The best alternatives to sharepoint are rated as following:
★★★★★  wiki
★★★★  alfresco
★★★  documentum
★★★  skydrive
★★★  quickr
★★  alfresco enterprise edition
★★  hyperoffice
★★  intrexx xtreme
★★  drupal
★★  google docs
★★  confluence
★★  salesforce
★★  dropbox
★★  wordpress
★★  google drive
★★  box
★  websphere
★  lotus notes
★  moss
★  onedrive
★  yammer
★  jive
★  livelink
★  basecamp
★  shared drive
★  eroom
★  access
★  google apps
★  sharepoint
★  expression web
  groove
  office 365
  .net
  joomla
  frontpage
  quickplace
  asp.net
  dotnetnuke
  exchange
  google sites
  public folders
  onenote
  microsoft access
  liferay
  huddle
  ibm connections
  sharepoint services
  sitecore
  intranet
  plumtree
  iis
  twiki
  drop box
  file share
  domino
  ektron
  moodle

Your alternative for sharepoint is not listed? Suggest!
Speaking about sharepoint, one probably shouldn't forget about office 365.

Other search terms related to sharepoint and their ratings are:
★★★★★ office 365
★★★★ access
★★★ nintex workflow
★★★ yammer
★★ ssrs
★★ frontpage
★★ tfs
★★ onenote
★★ infopath
★ ms access
★ access services
★ governance
★ sales automation project management
★ project server
★ office
★ .net
★ access 2010
★ visual studio
microsoft access
documentum
sharepoint designer
msde
You have in mind a companion for sharepoint and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of sharepoint in all years. Click on graph for more.
sharepoint
wiki
alfresco