You could use Perl's Proc::ProcessTable module.

Personally I'd create a text file with the services I was checking for, seperated by a colon like:

apache2:sshd:mysqld

Then I'd read that into the script and match it to the running processes using Proc::ProcessTable.

http://search.cpan.org/~durist/Proc-ProcessTable-0.45/Process/Process.pm should be able to get you started. Here's an ugly code that I threw together. It'll get the job done but there's much better ways to do it:

#!/usr/bin/perl
use strict;
use warnings;
use Proc::ProcessTable;
use Data::Dumper;

my $table = new Proc::ProcessTable( 'cache_ttys' => 1);
my @processes;

open(PROC, 'proc.check');
        while () {
                chomp;
                @processes = split(/:/);
        }
close(PROC);

foreach my $process (@{$table->table}) {
        foreach my $monitor ($process->{cmndline}) {
                foreach my $check (@processes) {
                        if ($monitor =~ m/$check/i) {
                                print "$check found running\n";
                        }
                        else {
                                next;
                        }
                }
        }
}

Output will be:

~$ perl check.pl
sshd found running
mysqld found running
mysqld found running
mysqld found running
apache2 found running
apache2 found running
apache2 found running
apache2 found running
apache2 found running
apache2 found running
apache2 found running
apache2 found running
apache2 found running
apache2 found running
apache2 found running
sshd found running
sshd found running
apache2 found running
apache2 found running

I guess its just a case of checking services are running I wrote a check script for a tru64 system once but seem to have lost it but its really write down all the services you think should be running then check them

i.e
ps -ef | grep http
telnet localhost 80

this is a basic check for a running apache server but there is much more you can do of course.. Really is such a wide requirements question you need to be a bit more specific in your question!