Over the past several years, I've used mainly CVS. I tried switching to subversion, which has been slow-going. To speed that process, I merged all of my repositories together into one svn repo. I also used cvs2svn.py to convert everything in cvs to svn, which put everything into /trunk/ in the repository - not what I wanted. A simple script fixes that:

repo=file:///path/to/repo
svn ls $repo/trunk | xargs -I@ -n1 svn mv $repo/trunk/@ $repo/@

I used svn poorly at first - one repository per project. To fix that, I needed to dump all of them (with svnadmin) and load them into a central repository:

# svnadmin dump all of my svn repositories
repodir="/home/foo
for i in $repodir/SVN/*; do 
  echo $i;
  svnadmin dump $i > $(basename $i).dump
done

# load all of my dumpped repositories into the new one
repo="/home/foo/NEWSVN"
svnadmin create $repo
for i in *.dump; do 
  proj="$(echo $i | cut -d. -f1)";
  svn mkdir -m "mkdir $proj for import" file://$repo/$proj
  svnadmin load --parent-dir $proj $repo < $i
done