Would you like to plan an outdoor party? I suppose this depends on weather and the time of year, as well as what is available in your neighborhood. We live near the beach and have hosted many successful beach parties. Sand castle contests, scavenger hunts, geocaching, etc. These are all fun outdoor activities.
One of the funnest things we ever did when our kids were young: build a giant fort out of fridge and stove boxes. We collected the boxes from appliance stores and used screws and wing nuts to build (way better than tape). You can do this indoors if you have room, then you can keep the fort. You can also do it outdoors, but that's not the best option in the winter. I could see this being an awesome birthday party. Make sure you have enough adults to help with the construction, though. I can imagine 5-10 seven year old boys might get bored during construction. Once it is done, though, they will amuse themselves for hours. Consider crayons or (washable) markers to allow them to decorate.
Outdoor super-soaker or nerf wars can be fun if the weather is cooperative. I also think geocaching is a fun activity and they are literally all over the city. We made our own indoor/ outdoor "treasure hunt" once by making fun clues/ accompanying pictures ("Go to where you might find a rubber duck") and we hid their loot bags at the end. You could also come up with a few "riddle-like" clues specific to your house/ pets that the birthday boy could feel special at being an expert at.
Many years ago my little son explained Christmas in the best way ever. He said that Christmas is a celebration of Jesus birthday. He said people give gifts to each other and have feasts and are happy. He said "It is almost as much fun as my own birthday."
Six months later I remembered this as I planned his birthday party. I hired Mike the Magician who put on a great show and wowed a large gang of kids.
I just ran across a really cool idea from a blog I follow on Tumblr. It has a tonne of fun/educational craft ideas for kids and this one particularly looks like something a 7 year old boy and his friend would enjoy. They could build their own Viking shields and then got into play battle!
Here's the link: http://bit.ly/1072hLD
Hope this helps. My friend Kristina at Par-T-Perfect (https://www.facebook.com/Par.T.Perfect.Victoria) also has a tonne of ideas and is so great to work with.
Good luck and look forward to hearing how it goes!
PS - Viking Adventures also looks pretty amazing but they're only open May through August...
I don't know if this is more than you wanted to spend, but we just had a birthday party for a bunch of 9 year-old boys at the SPCA. http://www.spca.bc.ca/youth/get-involved/birthd.... It was one of the best parties we've ever had for our son.
Partly it was fun because it was so different, and partly because it was engaging. We met Laura, the party leader, at the Burnside Campus where the SPCA has a party room. She was excellent. While there were crafts available, this particular group of kids were not interested in that, so after we learned how to pet animals in a non-threatening way, we walked over to the SPCA (about a five minute walk) and had an hour-long tour. There was lots of time for the kids to pet the animals (but not the dogs). After the tour we walked back and had cake and goodies. I was surprised how engaged the boys were in the animals ... they really got into this zone of petting and visiting with them. Honestly, I was pretty nervous as I hadn't heard anything about these parties, but it went off without a hitch and the kids loved it.