There are several different methods by which you can expand you Gridcoin holdings without spending a single penny of your own funds. The quickest way to obtain GRC is through the faucet system that several generous members of the community have setup. The faucets are designed to get newcomers familiar with digital currencies and to also give a small amount of Gridcoins to existing Boinc participants in order to welcome them into the Gridcoin ecosystem.
Gridcoin.asia Faucet: http://faucet.gridcoin.asia/
Rules: This faucet dispenses 1-3 Gridcoins every 3 hours and does not record IP address of past users. The only limitation is that the same IP cannot request coins within 3 hours of a previous request. This faucet is operated by a long-time member of Gridcoin community, sEpuLchEr.
Cryptospout's Hourly Gridcoin Research Faucet: https://cryptospout.com/faucet/hourly_gridcoin_research_faucet.html
Rules: This faucet dispense GRC every hour, but in much smaller amounts than the other faucets. The amounts are usually between 0.194 on the low end, and up to 0.389 on the high end.
Rules: The USCore page is run by GRC Nation, an enthusisat Gridcoin community based in Germany. USCore isn't really a faucet in the traditional sense, and users are required submit their email address in order to receive the free coins.
Another great way to receive and earn some GRC is to join the Gridcoin IRC chat on Freenode. Many members of the community frequently 'Tip' members of the chat group for helping out new members and contributing useful content. Sometimes you may even get tipped because someone just happens to be in a very generous mood:
There is another IRC channel where users can play various games and earn GRC for winning: Gridcoin-Games. The games do not require any monetary investment from users and are actually quite fun to play. Some games such as "Scramble" require users to decipher words in order to get a small 1-2 GRC reward. If you can't invest much or have some spare time to kill and want to have some fun, the games IRC channel is a great way to kill some time and maybe win some coins.
The official Gridcoin forum is full of generous members who frequently go out of their way to assist newcomers with advice and small amounts of GRC: https://cryptocointalk.com/topic/32833-starter-coins-for-beginners/