What to do with Minis

How do you guys show what a creature is on a game map if you don't have mini's?
I haven't DMd yet and my group hasn't played any sort of P&P RPing yet.

Also is there a way to buy specific minis pertaining to the Essentials Monster Vault?
Becuase I would like to start collecting/using them for my games.

It's tough to have no minis and alternatives are taking tokens and marking which way they face and their name. Since grids require lots of tactical movement, which ever way the baddie is facing makes a HUGE difference.

As for buying specific minis, most are those randomized booster packs or you simply buy the Essentials Monster Vault (Amazon and eBay are your friend!). Offline games require some arts and crafts with a bit of creativity but if you're online, Maptools (and the entire RPGtools for that matter) offer free and effective resources and programs to make maps and tokens for your maps.

Remember: Token size, name, and a marking of which way it faces is KEY.

Anyone know of a site online that sells a collection of minis?

Some games are not made for miniatures, and I find it doesn't take so much effort to imagine where things are. One example is World of Darkness, which is not made with miniatures explicitly in mind, same with the game RIFTs. Both definitely can be played with miniatures however.

And yes some people do find Miniatures handy both for visualizing their characters and for noting the locations of allies or enemies.

You don't have to buy minis, you could create tokens. I prefer them myself because you can either go the simple route (each PC is a color and the enemies are these numbered green ones) or you can go personalized, find pictures of everyone's character create tokens from those and then created tokens for each enemy.

Here is a nice tutorial to make your own tokens. http://newbiedm.com/2008/11/22/newbiedm-tutorial-counters-tokens-or-pogs/