It's never a bad thing to monitor, take a look; http://www.google.com/search?hl=en&safe=off&q=backlink+checker&btnG=
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do you know how many outbound links your blog have? How to check OUTBOUND LINKS with your world's most powerful ... ?
I don't think the overall number matters too much. It's more important that none of those have turned into broken links and none are linking to bad neighborhoods or blacklisted sites. I like to use Xenu to periodically check my sites for broken links.