Here's a good list: http://www.krispenhartung.com/software-looping.htm
I can't recommend any in particular, as looping isn't really my thing these days, though in the past I used Max/MSP or Pure Data to do it sometimes, but they are not a ready-made solution for looping (they're certainly capable of it though). Just I thought it's worth pointing out that basically any computer has the hardware you need to do looping built in (i.e. ADC + RAM + DAC), and there are lots of software solutions out there for it. Latency, which before ASIO was a big reason to go for hardware solutions instead of software, isn't even an issue when you're looping.
Last edited by rainwarrior (Apr 27, 2013 6:29 am)