Where to find specialized directories

[DeliaAssociates]

I'm looking to find some specialized directories, as I assist with a laboratory robotics group.  These can be paid (actually preferred for now) or free.  I know that seomoz has a helpful list of directories, but I was wondering if anyone else knows of a good place to find specialized directories like this.  Thanks.

[SlavaRybalka]

Google:

Science "web directory edited by humans" "submit link"

[SparkplugDigital]

Have you tried using advanced search operators? Here is a good guide: http://www.seomoz.org/article/the-professionals-guide-to-advanced-search-operators

Some possible searches that might work are:

allinurl:robotics directory

allintitle: robotics directory

robotics * directory

intext:robotics directory

[KeriMorgret]

You might try for some edu links too, if the product is something that is used by university labs. For an example local to me, if I was someone who sold surplus parts or metals or was targeting engineering students, I'd look at contacting some of the following following pages at Stanford from this query http://www.google.com/search?q=%22alan+steel%22+site%3Astanford.edu. This query is for Alan Steel, which is a local supply place. It gives me a lot of other pages where my hypothetical business might get a link

[DeliaAssociates]

Thanks everyone.  This has all been very helpful.