I won't sign Apache/Google-style CLAs either, because there's no way to terminate the agreement for any future contribution. Once you've signed, you're bound forever that anything you "submit" is a contribution - and basically everything is a contribution - from Google's CLA:

  For the purposes of this definition, "submitted" means any
  form of electronic, verbal, or written communication sent
  to Google or its representatives, including but not limited
  to communication on electronic mailing lists, source code
  control systems, and issue tracking systems that are 
  managed by, or on behalf of, Google for the purpose of
  discussing and improving the Work, but excluding
  communication that is conspicuously marked or otherwise
  designated in writing by You as "Not a Contribution."

For example, if you so much as talk to a Googler at the airport bar about a project you've signed a CLA for, bam, it's a contribution unless you remember to be explicit about saying "This is not a contribution". On the other hand, if you don't sign, only things that you explicitly mark as a contribution or otherwise suitably license are contributions, and someone who's signed the CLA is free to integrate it without needing to ask you.

I don't want some agreement following me around for life, and I don't want to have to disclose to every future employer that "Oh yeah, I've got an agreement with X that unless I remember to say otherwise X gets the rights to use it".

I'd sign a CLA that included a clause that said "This agreement may be terminated by either party in writing. Terminating this agreement does not revoke any licenses granted to the project while the agreement was in force."