The best replacement for clearcase is subversion.

The best alternatives to clearcase are rated as following:
★★★★★  subversion
★★★★  cvs
★★★  git
★★★  clearquest
★★★  perforce
★★  tfs
★★  synergy
★★  mercurial
★★  svn
★★  vss
★  rtc
★  pvcs
★  rational team concert
★  sourcesafe
★  accurev
★  team concert
  tfs 2010
  team foundation server
  tortoisesvn
  mks

Your alternative for clearcase is not listed? Suggest!
Speaking about clearcase, one probably shouldn't forget about hudson.

Other search terms related to clearcase and their ratings are:
★★★★★ hudson
★★★ jenkins
★ beyond compare
You have in mind a companion for clearcase and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of clearcase in all years. Click on graph for more.
clearcase
subversion
cvs