Do you aggregate?

Hi all, I hope most people on the list look at the routing table analysis reports. Excerpt from last week show about 292961 prefixes which after maximum aggregation can be reduced to 138493. I wonder how many of you do actually aggregate? If so, do you aggregate manually or using some algorithm? In either case (manual or automatic aggregation), how frequently do you aggregate? more frequent than the BGP updates frequency? If you aggregate, do you announce the aggregated prefixes or the original un-aggregated prefixes? how big is your network? (Tier-1, 2, 3, campus, etc.) I am hoping to get a few answers :) Regards, Zartash