Document and Bookmark Management. Create a program to scan for documents and bookmarks and let the user enter information about them into a database so they can search on it to find them easier. Allow users to share them, so others can find them. Make it so a business can index them on network drives for multiple employee use, and add in support for client/matter numbers, workgroups, and practice area indexing. The program can also pick the browser, or application to open up the document or bookmark with, which can be set by the user. Many people and businesses have a whole mess of unindexed documents and bookmarks scattered over computers, network shares, etc. Also have it import emails, which can be indexed as well.
Contact Management, keep track of contact info and have it indexed by client/matter numbers, workgroups, and practice areas. You can search on many fields, some are custom fields that the user can make up. Have it interface with Outlook, Act, and other PIMs. Put in PDA synching features.
Create a new open source OS that is easy to use, and can use driver models from Windows and Linux. Make it so that it has a Virtual Machine which can run other Operating Systems under it. Port GCC and other languages to it. Try to port WINE so that it can run Windows apps without needing Windows, otherwise Virtual Boot Windows in a virtual machine.