I use a program called VoxToFile.
It only records when there is activity and provides a log so you know what time the transmission occurred.
I provide a feed of the marine channels and Coast Guard for RR and a local boating forum. If someone posts a news story about an incident or asks what was the Coast Guard helicopter doing yesterday at 9 pm I can easily find the transmissions.
In my case a busy 24 hour period on the lake nets me 2 - 4 hours of recordings.
Here is an example of the log file. The start time (3rd column) is where I would go to in the sound file and it will correspond to the Date & Time.
Date, Time, Start, Finish, Duration
9/22/2009, 10:47:27 AM, 23:35.075, 23:38.081, 0:03.006
9/22/2009, 10:47:33 AM, 23:38.331, 23:42.339, 0:04.008
9/22/2009, 10:48:19 AM, 23:42.590, 23:44.093, 0:01.503
9/22/2009, 10:48:21 AM, 23:44.343, 23:48.351, 0:04.008
9/22/2009, 10:50:21 AM, 23:48.602, 23:51.357, 0:02.755
9/22/2009, 10:50:30 AM, 23:51.608, 23:54.864, 0:03.256
9/22/2009, 10:50:53 AM, 23:54.864, 24:01.127, 0:06.263
9/22/2009, 10:51:04 AM, 24:01.127, 24:04.383, 0:03.256
9/22/2009, 10:52:49 AM, 24:04.634, 24:12.149, 0:07.515
9/22/2009, 10:53:31 AM, 24:12.399, 24:19.163, 0:06.764
9/22/2009, 10:54:06 AM, 24:19.413, 24:20.916, 0:01.503
9/22/2009, 10:54:10 AM, 24:21.167, 24:27.680, 0:06.513
9/22/2009, 10:54:31 AM, 24:27.930, 24:32.690, 0:04.760
Matt