Lars Steiger and Stefan Fürst coached and pushed me to make Replies the product it is now. Their ideas, designs, and discussions were invaluable.
RBSplitView by Rainer Brockerhoff for the split views.
BWToolkit by Brandon Walkin for cool UI controls.
Sparkle by Andy Matuschak for automatic updates.
UKCrashReporter by Uli Kusterer to collect and send crash reports.