This extension provides email delivery for CiviMail and/or other email from CiviCRM via the Mandrill service. Mandrill is an email service that runs on the email infrastructure that powers MailChimp. It is a high quality, low cost option for email delivery, with no loss of delivery functionality, quality or performance in comparison with alternatives.
Payflow Link Payment Processor Extension
Stripe Payment Processor for CiviCRM.
Stripe is a wonderful payment processor that eliminates much of the headache for PCI compliance. Stripe.js securely transmits card details from browsers to Stripe.
Stripe is free to try, requiring only an email address and password to get started.
Stripe is also has no monthly fees, your costs are a small per-transaction fee + 2.9%.
It handles regular contributions as well as recurring through Stripe's subscription/plan feature.
Payment Processor for OMNGateway (now retracted)
This extension allows the admin to create and manage discount codes that can be used on membership and event pages.
Sagepay Payment Processor
Lookup the value of a given field based on the value of another field. For example, based on the postcode of a contact, on a contribution page or on an administrative page, you may want to lookup the region, district, state/province, or can be used to determine a medical clinic, closest office, etc.