Spam explosion

The quantity of spam around seems to be on the up - both at work where we reject really suspect connections and at home where I run mailfilter (which seems to be having problems deleting the bad stuff) and then use pop3 and postfix/procmail/spamassassin - I've recently started dumping the stuff with incorrect addresses into a folder which gets a cursory check so if you spell my email incorrectly I may not see it!
Here's yesterdays (home) log (abbreviated!)

Grand Totals
------------
messages

5467 received
5467 delivered
5037 forwarded
....
25384k bytes received
26223k bytes delivered
3251 senders
1986 sending hosts/domains
6 recipients
4 recipient hosts/domains


Per-Hour Traffic Summary

time	received	delivered	deferred	bounced	rejected
0000-0100	58	58	0	0	1
0100-0200	18	18	0	0	1
0200-0300	35	35	0	0	0
0300-0400	12	12	0	0	0
0400-0500	55	55	0	0	0
0500-0600	70	70	0	0	1
0600-0700	72	72	0	0	0
0700-0800	172	172	0	0	0
0800-0900	54	54	0	0	0
0900-1000	150	150	0	0	1
1000-1100	120	120	0	0	0
1100-1200	279	279	0	0	2
1200-1300	601	601	0	0	0
1300-1400	343	343	0	0	0
1400-1500	158	158	0	0	1
1500-1600	508	508	0	0	0
1600-1700	67	67	0	0	0
1700-1800	66	66	0	0	0
1800-1900	1322	1322	0	0	1
1900-2000	82	82	0	0	0
2000-2100	106	106	0	0	0
2100-2200	116	116	0	0	0
2200-2300	458	458	0	0	2
2300-2400	545	545	0	0	0

Yes, 1300+ emails an hour....at one point. Spam machines seem to have pretty well defined working hours! I think we receive around 30 non spam messages per day!