Comment G7 + Fusion-IO (Score 1) 205
My favorite boxes currently are HP-G7 with 2x 640 GB Fusion-IO and some hard disk. The data is in partitioned tables (MySQL 5.5), and I run for example 20 SELECT (partition-optimized) queries in parallel on them.
This is much faster (for me) than for example a Hadoop cluster. Mainly because the data is already where I query it. For me the copying of big data sets is the main bottle neck.
My aggregations normally finish in 1-5 minutes. One box does 60 GB per minute, 4 boxes do 90 GB per minute, so no big win by adding boxes.