Almost 100 404 not founds in my WMT

404's are more tough on your senses than anything.
Google really does not care much.
If they really bother you, best way is to actually
create a page that cannot be found.
Yes, 60+ is a little tedious.

If you can get over the sight of 404 errors, your
problem is licked.

Unfortunately, webmasters do not seem to like the
sight of any errors.

Google suggests that you make your 404 page with
some sort of look and feel that does not startle
a visitor. That is, a simple "not found" stock message will
scare off people. (keep in mind that for me, 99.99% of
404 errors are from search engines) You need some sort
of custom menu of links to get the visitor back on track.

Google even has a widget to put on your custom 404
page that will apparently try and find the closest match.
I have not used it, as I just have a navigation menu on
my 404 page. You can get google's help from:
Official Google Webmaster Central Blog: Make your 404 pages more useful
I have never used it as stated, and don't know if the widget still exists.
It should be in the google webmasters tools.

A custom 404 page would satisfy people and search engines.
Just turn your head when looking at the 404 errors and you'll
be set!

I don't use a robots.txt and google sure tries hard to find em.
Google will do strange things and assume that some pages are
there are try and crawl them.

In fact, you will probably never get all 404 errors to ever disappear.
Those nasty little typo errors, ya know.

Paul