As fiscal cliff ambiguity continues, some donors are increasing charitable contributions, while others are delaying gifts until the fate of tax deductions is made more clear.

If you're donating this year, you're probably well aware that midnight on Dec. 31 marks the cut-off for receiving tax breaks, but you may be not be aware of the best resources for giving.

If you're scrambling to make a last-minute contribution, you're in good company. Network For Good reports a huge spike in giving from noon to 7 p.m. on December 31.

What's more, the online giving site reports 10 percent of its donations come in on the last two days of the year.

If you're looking for suggestions on donating to worthy causes and tips on making major gifts, check out these sites below.

Charity Navigator
Charity Navigator is the ultimate reference tool for giving. Check out their A-Z directory for your major gift and take note of which charities have received the coveted four-star rating that takes into consideration accountability and transparency.

Network for Good
This site allows you to research 1.2 million charities and save you donation history and charity lists. If monetary donations aren't your thing, the site makes volunteering easy by providing opportunities through VolunteerMatch.

Causes.com
If your leanings are more grassroots, Causes.com provides a platform for do-gooders to create small movements centered around a cause that's important to them. Members have created 500,000 personalized causes and raised $40 million. Check out the causes people are talking about right now, make a gift, or -- if you're over 2011 giving and thinking about next year -- pledge to donate your birthday to a specific cause.

Razoo.com
This growing donation site helps you navigate 1 million officially registered nonprofit organizations. Check out popular causes of the week, make a gift or get a glimpse of who's donating what right now.

GreatNonprofits
It could be said that GreatNonprofits is the TripAdvisor for do-gooder organizations. It's the go-to site for people to post reviews of more than 1.2 million organizations. Check out the host of nonprofits ranging from animal welfare organizations to social justice nonprofits.

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  • Donations over $250

    For donations over $250, you must have documentation from the charity when you file, <a href="http://www.smartmoney.com/taxes/income/the-tax-perks-of-charitable-giving-11097/" target="_hplink">according to SmartMoney.com</a>. If the donation was in cash, the amount should be noted. If the donation was specific items, the organization must provide a description but does not have to value it.

  • Text donations

    For text message donations, a telephone bill meets the record-keeping requirement if it shows the name of the recipient, date and amount given, <a href="http://www.irs.gov/newsroom/article/0,,id=106990,00.html" target="_hplink">according to the IRS</a>.

  • Car donations

    The write-off for your donated vehicle depends on how the organization uses it. When you donate, the IRS gets a copy and checks car donation specifics closely, <a href="http://www.smartmoney.com/taxes/income/the-tax-perks-of-charitable-giving-11097/" target="_hplink">according to SmartMoney.com</a>.

  • Donations You Can't Deduct

    You can't deduct contributions made to specific individuals, political organizations and candidates, <a href="http://www.irs.gov/newsroom/article/0,,id=106990,00.html" target="_hplink">according to the IRS</a>. If you received something such as show tickets because of your contribution, then you can only deduct the amount that exceeds the fair market value (generally agreed upon selling price) of the item, <a href="http://www.irs.gov/newsroom/article/0,,id=106990,00.html." target="_hplink">according to the IRS</a>.

  • Surprising Deductions

    If you hosted an exchange students last year, you can deduct up to $50 per month for each month the students stayed with you, <a href="http://finance.yahoo.com/news/charitable-donations--what-you-need-to-know.html" target="_hplink">according to Yahoo! Finance</a>. In fact, if you hosted the students for 15 or more days, that counts as a full month. If your student was enrolled as a full-time student at a U.S. school, was placed in your home through a qualified organization, and is not your relative, go ahead and deduct. Volunteer work does not yield a deduction, but transportation to and from the event, however, can mean a deduction, <a href="http://www.irs.gov/newsroom/article/0,,id=106990,00.html" target="_hplink">according to the IRS</a>.