Magento Create Limited & Random Product List.

In my case i have create featured product list with product 10 and it display randomaly.
Please copy past following code in your collection block file.

protected function _getProductCollection()
{
        if (is_null($this->_productCollection)) {
            $collection = Mage::getModel('catalog/product')->getCollection();
            $collection
            ->addAttributeToSelect(Mage::getSingleton('catalog/config')->getProductAttributes())
            ->addMinimalPrice()
            ->addFinalPrice()
                    ->addAttributeToFilter('featured_product', 1)
            ->addTaxPercents();
            $collection->getSelect()->order(new Zend_Db_Expr('RAND()'));
            $collection->setPage(1, 10)->load();

            Mage::getSingleton('catalog/product_status')->addVisibleFilterToCollection($collection);
            Mage::getSingleton('catalog/product_visibility')->addVisibleInCatalogFilterToCollection($collection);
            $this->_productCollection = $collection;

        }
        return $this->_productCollection;
}

Magento Sort Category(Navigation) By Name or Alphabatically.

To sort Top Menu Categories and its Sub-Categoiries alphabetically,

Copy app/code/core/Mage/Catalog/Block/Navigation.php to app/code/local/Mage/Catalog/Block/Navigation.php OR you can override the same file in your local

public function toLinearArray($collection)
{
        $array = array();
        foreach ($collection as $item) $array[] = $item;
        return $array;
}

protected function _sortCategoriesByName($cat1, $cat2)
{
       return strcasecmp($cat1->getName(), $cat2->getName());
}

In Navigation.php edit the function _renderCategoryMenuItemHtml(), add the following 2 lines before the code $hasChildren = ($children && $childrenCount);

$children = $this->toLinearArray($children);
usort($children, array($this, '_sortCategoriesByName'));

If you need to sort Parent Categories too, use below code before your foreach loop when you display category list

<?php $helper = Mage::helper('catalog/category') ?>
<?php $categories = $helper->getStoreCategories(); ?>
               
<?php $children = $this->toLinearArray($categories);
usort($children, array($this, '_sortCategoriesByName'));?>
   
<?php foreach ($children as $_category): ?>
<?php echo $this->drawItem($_category) ?>
<?php endforeach ?>

Magento Product Attribute Show/Hide in Admin Depending on Other Attribute Value

Please past this code in design/adminhtml/catalog/product/edit.phtml

<script type="text/javascript">

    Event.observe(window, 'load', function() {
        var $delDay = $("featured"); // featured is yes/no dropdown id
        if ($delDay.value == 0) {
        $('featured_position').value = ''; // delivery_time is show.hide attribute name
        $('featured_position').disable()
        }
    });

    Event.observe($("featured"), 'change', function() {
        var $delDay = $("featured");
        if ($delDay.value == 1) {
            $('featured_position').enable();
        }
        else {
            $('featured_position').value = '';
            $('featured_position').disable();
        }
    });
</script>

Magento Install GeoIP Extesion

In following link you can get GeoIP Extesion.
This extension allows you to use free GeoIP Lite database by MaxMind with your Magento installation. 

http://www.magentocommerce.com/magento-connect/geoip.html

Magento Create Custom Attribute in Category

1) Yes / No Dropdown

<?php

$installer = $this;
$setup = new Mage_Eav_Model_Entity_Setup('core_setup');
$installer->startSetup();
$setup->addAttribute('catalog_category', 'is_catalog', array(
   'type' => 'int',
    'group' => 'General',
    'backend' => '',
    'frontend' => '',
    'label' => 'Is Catalog ',
    'input' => 'select',
    'class' => '',
    'source' => 'eav/entity_attribute_source_boolean',            // Leave blank for input type text box
    'global' => Mage_Catalog_Model_Resource_Eav_Attribute::SCOPE_GLOBAL,
    'visible' => true,
    'required' => false,
    'user_defined' => false,
    'default' => '0',  //Leave blank for input type text box
    'searchable' => false,
    'filterable' => false,
    'comparable' => false,
    'visible_on_front' => false,
    'unique' => false
));
$installer->endSetup();

2) Textbox

$installer = $this;
$setup = new Mage_Eav_Model_Entity_Setup('core_setup');
$installer->startSetup();
$setup->addAttribute('catalog_category', 'my_attribute', array(
'group' => 'General',
'input' => 'text',
'type' => 'varchar',
'label' => 'My Attribute',
'backend' => '',
'visible' => 1,
'required' => 0,
'user_defined' => 1,
'global' => Mage_Catalog_Model_Resource_Eav_Attribute::SCOPE_GLOBAL,
));
$installer->endSetup();

Magento Reindex Programmatically

for($i=1;$i<=9;$i++){
    Mage::getModel('index/process')->load($i)->reindexEverything();
 }

 // where I is

 1 = Product Attributes
 2 = Product Attributes
 3 = Catalog URL Rewrites
 4 = Product Flat Data
 5 = Category Flat Data
 6 = Category Products
 7 = Catalog Search Index
 8 = Tag Aggregation Data
 9 = Stock Status

Magento Clear Cache Programmatically

Mage::app()->cleanCache();