You can use Kinesis Firehose to stream data to S3. It'll buffer data for a while -- you set thresholds based on size of data or time, whichever is hit first --

You can use Kinesis Firehose to stream data to S3. It'll buffer data for a while -- you set thresholds based on size of data or time, whichever is hit first -- then it will save the data to S3. It won't be a single large file, but they'll all have the same prefix based on date. Most data processing tools will let you suck up an entire prefix and treat it like a single file.