Know that to get money on the side, you'll need to become popular enough to get a sponsor. That's easier said than done. Nevertheless, here are some channel ideas...
-- Video game walkthrough... if you have a cool fun personality. If you don't have an energetic awesome personality who can make great jokes, it won't work.
-- Music channel. If you know music, you could do covers of songs-- make them stand out from the rest by good editing and sound equipment. If you don't know music, you could start a channel where you teach yourself guitar and part of a vlog about tips and mistakes of what you are doing.
-- Generic college vlog. If you have a lot of interesting things that happen in your life, go ahead and make a vlog for your life. Check out the college party life. Make a vlog for all the incoming college students just like you.
-- Tutor. If you are smart, do youtube videos where you explain math stuff for younger students in high school or junior high (like algebra stuff). To stand out from the rest, do it in a relatable "bro" way. Make sure you make jokes and keep it super interesting.
-- Prank. If you are a prankster, make pranking videos around campus like Jstudios (I think that's their name?) does. Ask youtube viewers for their prank ideas too. Do this if you have no shame and are willing to prank people. Oh, and make sure you have a friend with good camera skills and a mic system.
Hell, if you wanted to, you could an internet prank channel too. If you are a great troll, funny omegle guy, or whatnot, this will work.
Other than that, you can do whatever your passion is. If you are good at art, make an art channel. If you're good at cooking, do a cooking channel -- maybe making college food on a college budget with stuff you'd find on campus. People will like what you like if you can sell it.
In any channel though, the key is a good personality. People want likeability, good camera work (no shakey cam with crappy potato 240p), and often someone funny. Don't be a jerk.
And let's be honest... Attractive looks help.