I am looking for a site that allows me to type in a URL of a company,
and then see how many other sites link to that one...

Hello Stus-ga ~

The problem with any link checker is, of course, that it has become
aware, through some source (usually a search engine or other database)
of sites that that are linked to others.

1. Google's Link: tool
======================

I would first recommend Google's link: tool - which allows you to
enter link:yourURL into the Google search box and will return pages
linked to that URL.  Google's link: tool is explained here:
   - ://www.google.com/help/features.html#link

It is generally believed that Google only returns links with a
Pagerank of 4 or more, although I have seen occasions where linked
pages with a lower Pagerank have been returned.

Information about the significance of Google's Pagerank can be found
here:
   - ://www.google.com/technology/index.html


2. Alltheweb.com
================

All The Web - http://www.alltheweb.com - allows you to enter a URL and
then it's return page gives you an opportunity to click a link that
delivers the number and pages that link to that URL.

When I entered "google.com" into Alltheweb's search, it returned the
following:

"Find all 21,468,186 external web pages that link to "google.com""
and
"Find all 4,507,801 external web pages that contain the term
"google.com""


3. Marketleap's Link Popularity Checker
=======================================

Marketleap offers this tool claiming, "Link popularity analysis is one
of the best ways to quantifiably and independently measure your
website's online awareness and overall visibility. Simply put, link
popularity refers to the total number of links or "votes" that a
search engine has found for your website."

They allow comparisons of up to three URLs with this feature and offer
the reminder that link popularity is constantly changing due to the
dynamic structure of the Web.

You can try their Link Popularity Checker here:
   - http://www.marketleap.com/publinkpop/


4. Software you can install
===========================

In addition to the three tools above, there is software available to
purchase and install such as the following:

* Antsoft's LinkSurvey
   - http://www.antssoft.com/linksurvey/

* Link Popularity Analysis
   - http://www.link-popularity-analysis.com/

* Web Link Viewer
   - http://www.gradetools.com/linkviewer/lwmain.htm


A word of warning about using the type of software you install
yourself. Google warns against using such software for submission in
its "Quality Guidelines - Basic principles":

"Don't use unauthorized computer programs to submit pages, check
rankings, etc. Such programs consume computing resources and violate
our terms of service. Google does not recommend the use of products
such as WebPosition Gold™ that send automatic or programmatic queries
to Google."
   - ://www.google.com/webmasters/guidelines.html


Search terms used:

 - site link analysis
 - website link analysis


This should give you some tools to use and compare for checking and
alalyzing links.

Regards,
Serenata

Very complete!