Just a few questions to see if you've even bothered to think about this beyond "Websites are cool, open is awesome!"...
These questions all come from firsthand experience.
1) Who will maintain the data on the site?
a) Does the city have the budget for them to do this?
b) Will there be resistance to the amount of work they have to do / training they have to take?
c) Will you train them?
2) What do the solicitors think? Will they even let you post what you want on the site?
3) Do the departments want the information available? Are they going to push back if they don't?
4) You have no budget. Who pays for or does the hosting? Registration? Admin stuff? Maintenance?
5) Do you actually have buy-in from the people you need it from, or are they just humouring you?
6) Are you being used? This is the sort of thing that municipalities (Yes, even your small one. Look at its tax roll sometime) can easily justify dumping $20k+ into
7) They have done a feasibility study, right?
8) How familiar are you with accessibility standards? Are there some you legally must meet to even put the site up?
9) Who is responsible for the site itself?
10) Are you prepared to have this project drag on for over a year?
11) Finally, the hardest one - are you certain you know the scope of the project?
Good luck, but don't get yourself in trouble...