I guess this is a pretty good OS X tarsnap configuration.

.tarsnaprc

### Recommended options
humanize-numbers

# Tarsnap cache directory
cachedir /usr/local/tarsnap-cache

# Tarsnap key file
keyfile ~/.tarsnap/tarsnap.key

# Don't archive files which have the nodump flag set
nodump

# Print statistics when creating or deleting archives
print-stats

# Create a checkpoint once per GB of uploaded data.
checkpoint-bytes 1G

# Exclude files and directories matching specified patterns
exclude Libraries/
exclude Dropbox/
exclude Library/
exclude Music/
exclude Public/
exclude *.app/

exclude Documents/Projects/
exclude Applications/
exclude Applications (Parallels)/
exclude Creative Cloud Files/
exclude Documents/Virtual Machines.localized/

# Developer Trash
exclude .cache/
exclude .cocoapods/
exclude .gem/
exclude .heroku/
exclude .itmstransporter/
exclude .node-gyp/
exclude .npm/
exclude .rbenv/
exclude .plugman/
exclude .dropbox/
exclude Documents/dotfiles/.git

# Random trash files
exclude $RECYCLE.BIN
exclude *.cer
exclude *.ini
exclude *.mobileprovision
exclude *.tmp
exclude ..*
exclude .DS_Store
exclude .Trash
exclude .Trash/
exclude .localized

# Don't really need these
exclude *.zip
exclude *.pkg
exclude *.iso
exclude *.dmg
exclude *.exe

# Exclude SQL Backups, since they're already on S3
exclude *.sql.bz2

# Media Files are very large
exclude *.flv
exclude *.mp4
exclude *.mov

exclude Pictures/
exclude Documents/Photos/
exclude Movies/

com.dlo.tarsnap.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
  <dict>
    <key>Label</key>
    <string>com.dlo.tarsnap</string>
    <key>RunAtLoad</key>
    <true/>
    <key>EnableGlobbing</key>
    <true/>
    <key>StartCalendarInterval</key>
    <dict>
        <key>Minute</key>
        <integer>0</integer>
    </dict>
    <key>ProgramArguments</key>
    <array>
        <string>/bin/bash</string>
        <string>-c</string>
        <string>/usr/local/bin/tarsnap -cf "$(sysctl hw.model | awk '{ print $2 }') $(system_profiler SPHardwareDataType | awk '/Serial/ {print $4}') $(date +\%Y\%m\%d-\%H\%M)" .</string>
    </array>
    <key>WorkingDirectory</key>
    <string>/Users/dan</string>
  </dict>
</plist>

com.dlo.tarsnapper.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
  <dict>
    <key>Label</key>
    <string>com.dlo.tarsnapper</string>
    <key>RunAtLoad</key>
    <true/>
    <key>StartCalendarInterval</key>
    <dict>
        <key>Minute</key>
        <integer>30</integer>
    </dict>
    <key>ProgramArguments</key>
    <array>
        <string>/bin/bash</string>
        <string>-c</string>
        <string>tarsnapper --target "$(sysctl hw.model | awk '{ print $2 }') $(system_profiler SPHardwareDataType | awk '/Serial/ {print $4}') \$date" --deltas 1h 1d 7d 30d 365d 18000d - expire</string>
    </array>
    <key>WorkingDirectory</key>
    <string>/Users/dan</string>
    <key>EnvironmentVariables</key>
    <dict>
      <key>PATH</key>
      <string>/bin:/usr/bin:/usr/sbin:/usr/local/bin</string>
    </dict>
  </dict>
</plist>