The Thomas the Train snack train I made for my son's third birthday. It was so easy and cheap to make. It's just 3, two packs of aluminum loaf pans from Walmart at 2.50 each (mine came with plastic lids-great for leftovers), a roll of black electrical tape (.60 cents) and of course, Thomas. We had our Thomas, didn't have to buy one.
Choo Choo Arron is Three! A Thomas the Train Inspired Party
This site has a collection of several awesome Thomas or train themed parties. I think some of these ideas are ones I could use for Eli's 2nd :) From:The Blog Formerly Known As Come Together Cards, now Courtney Warren Creative: Train Birthday Party: Best of the Web