Now, if you begin to grow such traffic that you need to shell out $100/mo in hosting, then maybe you have something interesting going that you can probably find a way to make some revenue from it (or at least $100/mo)
There is always the option of using S3 or App Engine, but it really depends on your app. So, if your goal is Resume Building, at least start with cheaper hosting and build a prototype.
I use a VPS that costs me $49/mo and I use that for hosting any prototypes or early projects.
I really don't think most of the hobby projects are paying anywhere near $100/mo for hosting. Is there something specific about your project that would need a $100/mo webhost?
seriously, almost every real SysAdmin has a server in a datacenter somewhere, roaring away and burning through power, often doing little more than personal email, spamfiltering, and personal website/filesharing. Usually they love giving friends free hosting for little personal projects, as that justifies the existence of that co-located box that allows the SysAdmin to keep his or her skills up to date. You know how open source programmers are proud when other people use code they provide? SysAdmins feel similarly when we get to host/support something cool.
I mean, if you were employed, I'd say to go buy a VPS (unless your idea involves streaming movies or, ah, 'adult content,' there is no reason why your hosting bill needs to be more than $20/month. Less if you are willing to deal with a underpowered server, or one of the 'up and coming' providers.)
Even the costliest is only $19/mo.