<p>Can somebody in SO please provide me with a list of resources about Enterprise Mashups and technologies related to SharePoint platform?</p>

<p><strong>Update</strong> (as per suggestion of @Spoon16 in the comments):-
The mashup application may typically retrieve a list of contacts from a SharePoint site and display the address of a selected contact person on a map (again maybe Google maps).</p>

There are a number of different ways to pull external information into SharePoint.
For mashing up SharePoint data in external applications:
Web Services
; great web services coverage for the underlying API will allow you to build external mashups (like the one you mention in your question comment).  Specifically take a look at the
Lists Service
.
For mashing up external data sources inside of SharePoint:
Business Data Catalog
; when you have the enterprise version of Microsoft Office SharePoint Portal server you can use the Business Data Catalog to interact with a very wide variety of external datasources in a read/write fashion.  Works with relational databases and web services.
Enterprise Search
; the indexing capabilities provided by SharePoint's Enterprise search technology are extensive
RSS Web Part
; allows you to consume and apply XSLT transform to any RSS feed and output the result on any SharePoint page
Page Viewer Web Part
; allows an iframe to be embedded on any page, provides an easy mechanism of integrating external applications into the SharePoint environment
SharePoint has an
extensive development framework
that enables you to leverage the full capabilities of the .NET framework to make your wildest mashup dreams come true.  You can use even add additional services to SharePoint that expose the underlying data in custom ways (not covered by the Out of the Box web services) if you like.