I'm a sucker for drum machine apps, and at this price who can argue?

It looks great for $0.99. Here are the details:

Beat-Machine is a powerful retro themed drum computer for iOS. It combines a simple X0X style sequencer with a robust and flexible sampler to give you maximum control over your beats.

Features:

• Sound sampler with reverse, sample trim, interpolation, ADSR and filter
• 16 Levels mode for pitching samples to create melodies
• Full mixer with volume, pan and 2 FX sends per pad (Delay, Reverb)
• Mute grid for programming samples to mute other samples
• Import any 16/24 bit WAV via iTunes file sharing
• Create custom kits and save them
• 16 step muti touch pattern sequencer
• Adjustable pitch and velocity per step
• Create and save custom patterns
• Create patterns in 2/4, 3/4, 4/4, 5/8 or 7/8 time signature
• Up to 99 measures per pattern
• Beat quantize adjustment slider
• Adjustable latency and sample rate
• Background audio
• MIDI IN, MIDI OUT supported through CoreMIDI accessories and WiFi
• Universal app designed for iPad, iPhone, and iPod touch
• MIDI support