Bill , there are some things you can do .
I moderate (but do not own) a very active hobby forum and I feel your pain .
There are 2 websites I find very helpfull in checking new registrations .
First and foremost is.....
Click on "search" and enter an IP address , it will show you if that address has been reported as a spam IP .
Then you can ban or delete the profile .
Most spammers are "bots" and usually wait a few days after registering before coming back and doing their thing .
Some , maybe 10% , spam immediately .
I prefer to ban rather than delete , in VBulletin forum software when you ban a profile the email address used cannot be used again , if you delete the profile they may just use it over and over .
I'm not up on the inner workings of phpBB forums , but if you look through that site you may be able to add script that will automatically check new registrations for you and block any IP address in the database .
If you check new members manually , check IP , email , and username .
If I don't get any "hits" on that website and I'm still suspicious , I check the IP address here....
Anything out of China , The Russian Federation , India , Pakistan , and most Eastern European countries are spammers sad to say , even if they are not listed (yet )in the database at Stopforumspam .
On even the most well protected forum spam is gonna happen every so often , it's a given fact .
It may be irritating to the members , but the best thing is to just ignore it and hit the "report post" button when it slips in .
Hard as you try , some is gonna make it through .
Nice forum and I hope it continues to grow !