There are places where you can go to and they have mapped out areas of each shard, mainly Luna and tokuno so people can pinpoint what vendor has what stock at that percise moment. These sites, although used by many players, are frowned upon because they use 3rd party programs / scripts to scan the vendors and also they are not exactly UO endorsed progs to use.
I run a vendor house on Europa, so a few things i will say in order to help with your business (some of which has been said before) is as follows: -
1. Talk to other shop owners, I have become very friendly with other shop keepers on Europa. Not only does this bring new friendships but also alows trade of stock between shop keepers. For example, if i did an idoc and got 10 bottles of 50 charge tokuno pigments but i dont generally sell them i may swap them with another shop keeper for an item that i do stock but im running low in back up supply of.
2. Dropping runes is good. However as you saywe cant play all day. So if you have rented out vendors, encourage them to gate and drop runes to your shop to aid the advertising. Maybe if they actively do this you could offer an incentive like dropping the rental price on their vendor?
3. Advertise the fact that you have a shop on your shards strats forum. Although it seems like it is people that are only after high end stuff that trawl the board, so do a lot of people looking for the "everyday needs".
4. Do rune trades!! Offer shop keepers the opportunity to lock down a rune to their shops on your steps or in a runebook to other shops that you keep locked in a prominent possition (with access to the runebook set so anyone can view inside), in return they do the same for you. just keep checking the runes to ensure your spot is being advertised.
5. This IS the big one. Keep well stocked. People like to know they can click to one shop and find the item they are looking for. I know its impossible to keep every item in UO stocked and up for sale in your or any shop 100% of the time theres a limit to how much 1 person can possibly have. However make it a routine to stock up every other day or everyday so people make you their first port of call. Keep running out they will look elsewhere.
The directory would be a good idea. Shops on all shards located in one directory, i could see that working.
Hope this post helps and if i gone off the point then my excuse is its late and im tired
