Magento 1.9.x source model list. Source: http://www.extensions.sashas.org/blog/magento-source-models-list.html

magento-source-model-list

Model	Description
adminhtml/system_config_source_admin_page	returns list of all the items in Magento Admin menu
adminhtml/system_config_source_allregion	returns list of all country regions grouped by country
adminhtml/system_config_source_catalog_timeFormat	returns time format (12h or 24h )
adminhtml/system_config_source_cms_page	returns list of CMS Pages
adminhtml/system_config_source_cms_wysiwyg_enabled	returns list of text editor options
adminhtml/system_config_source_country	returns list of all countries from directory module
adminhtml/system_config_source_cron_frequency	returns list of cron frequence ( Daily, Weekly, Monthly)
adminhtml/system_config_source_currency	returns list of currencies
adminhtml/system_config_source_customer_group	returns list of customer groups
adminhtml/system_config_source_date_short	returns list of available short date formats
adminhtml/system_config_source_design_robots	returns list of robots options (index, follow)
adminhtml/system_config_source_email_identity	returns list of email sending identities (General Contact, Sales Representative, etc)
adminhtml/system_config_source_email_method	returns list of email methods (Bcc, Separate Email)
adminhtml/system_config_source_email_template	returns list of transactional email templates
adminhtml/system_config_source_enabledisable	returns list of two options (“Enable” and “Disable”)
adminhtml/system_config_source_frequency	returns list of frequencies (Always, Hourly, Daily, Weekly, Monthly, Yearly, Never)
adminhtml/system_config_source_locale	returns list of locales
adminhtml/system_config_source_locale_country	returns list of localized country names
adminhtml/system_config_source_locale_currency_all	returns list of localized currency names
adminhtml/system_config_source_locale_timezone	returns list of localized timezone names
adminhtml/system_config_source_locale_weekdays	returns list of localized weekday names
adminhtml/system_config_source_notification_frequency	returns array of hours frequency ( used for cron)
adminhtml/system_config_source_notoptreq	returns list of three options for customer widget mandatory indetificator (“Not”, “Optional”, “Required”)
adminhtml/system_config_source_order_status	returns list of available order statuses except pending payment
adminhtml/system_config_source_payment_allmethods	returns list of all payment methods
adminhtml/system_config_source_payment_allspecificcountries	returns boolean values for payment (“All Allowed Countries”, “Specific Countries”)
adminhtml/system_config_source_price_scope	returns list of price scopes
adminhtml/system_config_source_shipping_allmethods	returns list of all shipping methods
adminhtml/system_config_source_shipping_allspecificcountries	returns boolean values for shipping (“All Allowed Countries”, “Specific Countries”)
adminhtml/system_config_source_shipping_taxclass	returns list of tax shipping classes
adminhtml/system_config_source_store	returns list of stores
adminhtml/system_config_source_tax_basedon	returns list of values which tax based on
adminhtml/system_config_source_yesno	return boolean options (“Yes”, “No”)
checkout/config_source_cart_summary	return list of display options at the cart