Do I need permission to repost menus online?

Compiling restaurants' menus and contact information is permissible. The menus may be covered by common law copyrights, but I doubt that anyone would bother to enforce any limits on using them. In fact, I would think that the owners would be thrilled to have you promoting their business. Likewise, their location, hours, etc. is public information.

There are no restrictions on the use of mapping applications offered by Google, Yahoo, and others that would prohibit this use.

Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.

It is possible that some doodle or witty description of an item would be covered by copyright. There is probably a greater chance of you being struck by a meteor on the way to cash in your Powerball jackpot winning ticket than of anyone being anything but happy that you're advertising their business. If you want to be cautious, you could strip out anything artistic or clear your use with the restaurant.

I have a different perspective.

Menus are unquestionably protected by copyright. The direct answer to your question, therefore, is that it's an infringement of the copyright in the menu for you to digitize it (i.e., copy it) and to then upload it onto your website (i.e., publish and/or distribute it). While the restaurant owner MAY not object, your business plan is inherently unlawful. Not the best way to start off.

If I owned a restaurant I may just object to your uploading a copy of my menu onto the internet. Items on menus and their prices change frequently. I would not want the public to rely on outdated information about my food and prices that it learned from your website. That sets up an awkward (at best) situation when the person discovers the information is outdated and he or she cannot get the steak tartar for $11.50 any longer (if at all -- I'm thinking mad cow).

There are many websites that list the food items available at various restaurants and the price of the food. Few, if any, upload the menus themselves.

I would seek permission from the local restaurants to upload their menus and, via a written agreement, put the onus on the restaurant owner to ensure that you have an updated version of his or her menu.