You could check out Oracle's Application Express. It's free and it's geared toward Access developers.
It has a migration assistant as well that you run your Access database through, it proccesses the data and the forms, migrates everything to an Oracle Database (this works with the free database, Oracle XE, and comes install by default) and builds web forms for your Access database.
So in the end you'll have your Access databases on the web, your data in Oracle and somewhat nice web front end for extending them.
As far as Oracle goes, the tool isn't half bad. You can sign up for a free instance to play around with here.
Here's the document that explains how you migrate Access Databases.