Put your URL on all stationery
Even online businesses may need stationery so it's vital to include your URL on all paperwork, letterheads, invoices, business cards, compliment slips etc.
In my offline business I have found a great way of boosting my website traffic to www.uk-cartoonists.co.uk
We despatch our products business-to-business and direct to the consumer through the post or by courier and I obviously include packing slips, compliment slips etc. These are run off our b&w laser printer, when we set up our website I put an "ad" on the slip pointing customers to our website.This has proved v.successful in terms of hits.
More recently, though, I have used a fluroscent highlighter to mark the URL on the slip.
You wouldn't believe the increase in hits!!