Julie Rehmeyer's August Math Trek column in Science News talks about the Online Encyclopedia of Integer Sequences and its creator Neil Sloane. The OEIS currently has almost 200,000 integer number sequences in an online searchable database. This is a passion for Sloane begun in the mid-1960s while in graduate school.
From the article, "the OEIS ... provides a sequence’s full 'life story.' Along with listing the numbers that form the beginning of a sequence (sometimes hundreds of thousands of them), it gives all the different known ways to generate the sequence, lists references to the sequence in the scientific literature, links to any sites with information about it, cross-references related sequences, provides a graph of the sequence, and even offers a way to listen to the sequence."
It is very easy to lose yourself for hours in the OEIS so be careful ;-).