For the countries that have visa on arrival services, just show up at the border with your passport and receive the visa stamp. For most countries, you only need to have a valid passport, address proof and photographs to get the visa stamped at the airport or at the land borders.
Nepal- Visa on arrival at the airport for 15-30-90 days.
Maldives- 30-day free-visa is issued on arrival for all nationalities.
Cambodia: 30 day visas are available on arrival at any land borders and at the airports.
Indonesia: A 30 day, visa is available on arrival at the seaports and airports in Indonesia. The cost is $25. You can extend your visa when you are in the country for a further 30 days.
Laos: A 30 day visa is available on arrival at the border and at the airport in Laos. The price of the visa varies depending on which country you are from.
Malaysia: A free, 90 day visa is available on arrival at the airport and at the land borders. This applies to most, if not all, western countries.
Philippines: 21 day visa is available on arrival at the airport. You can apply for a 59 day visa ahead of time at the Philippine Embassy in the country of your choice, or, you can extend the 21 day visa once you are in the Philippines.
Thailand: 30 day visa is available on arrival at the airport for most nationalities (all Western countries included). For entry to Thailand by land, a free, 15 day visa is available on arrival. If you want to stay for 60 days, you will need to apply for a visa at the Thai Embassy.
Singapore: 30-90 day (depends on your nationality) visa is available on arrival at the land borders and at the airport. This applies to all western countries.