/var is lack of space!!

[heccj]

My box has Apahce,PureFtp,MySql services, it's hardware:128M memory,
i386 FSB 800Mhz,18G SCSI disk,FreeBSD 5.3.It's slice:
/	256M
/swap	256M
/tmp	256M
/var	300M
/usr	others
After installation,the useage is about 20%.But after few days,
it increases 50%,so i moved the http and ftp logs,mysql data to another
slice,but after several days it increases to 70%,now almost 90%.Perhaps
my box will crash serveral days.I checked the /var/log,it only use about
20M,/var/tmp only 100k.So who and where used the space?How should I do?

thanks every one,itis the first time i use freebsd's mailist.