_(Lambda calculus) is not only an abstract calculus, but an *(Abstract VM): a kind of calculus of very basic abstraction. It was invented even before Turing Machines, also as a universal computational framework. Check pages and books about _(functional programming), _(functional programming language)s, computer science laboratories, theoretical computer science research, etc, for more about lambda calculus.

A few pointers: 
<ul>
<li>See the series of "Lambda, The Ultimate <var>X</var>" articles. In the original ones by GLS, <var>X</var>={<a href= "ftp://publications.ai.mit.edu/ai-publications/0-499/AIM-353.ps">Imperative</a> | <a href= "ftp://publications.ai.mit.edu/ai-publications/0-499/AIM-379.ps">Declarative</a> | <a href= "ftp://publications.ai.mit.edu/ai-publications/0-499/AIM-443.ps">Goto</a>, Opcode}. They are available among other classic hits MIT AI lab publications. 

<li>On the "Lambda, The Ultimate <var>X</var>" trend, <var>X</var> has been { software tool | label | combinator | ``little language'' }. This <a href= "ftp://publications.ai.mit.edu/ai-publications/1500-1999/AIM-1564.ps.Z">W7</a> article by <a href="http://mumble.net/jar/">Jonathan Rees</a> <em>could</em> have been called "Lambda, the ultimate security construct".

<li>Finally, <a href="http://www.unlambda.com/~james/">James Crippen</a> collected fortune cookies that have the <a href="http://www.unlambda.com/~james/lambda/lambda.txt">Lambda nature</a>, many of which are but exerpts from <a href="http://www.cs.cmu.edu/csd/perlis.html">Alan Perlis</a>' "<a href="http://www.cs.yale.edu/homes/perlis-alan/quotes.html">Epigrams in Programming</a>".

<li>Several programming languages have a strong basis in the lambda-calculus, including:
<ul>
<li>_(Lisp)
<li>_(ML)
<li>_(Haskell)
<li>_(Clean)
</ul>
</ul>
