So far in 2011 more than 200 new exchange-traded products have debuted, taking the ETF lineup close to the 1,300 mark. Over the past several years, the exposure accessible through ETFs has become increasingly granular; while some of the new products debuting are "plain vanilla" funds linked to well known indexes (such as the recent debut of SCHZ), the vast majority of new additions offer targeted exposure to specific markets or sectors or somewhat complex investment strategies involving multiple asset classes or sub-classes. 

The ETF coverage map is becoming more and more complete; investors now have at least one option for accessing many of the world's most important economies. There is now a Cloud Computing ETF (Nasdaq: SKYY), a Fertilizer/Potash ETF (NYSE: SOIL), and an Ireland ETF (NYSE: EIRL). The complaints about over-saturation in the ETF space began about two years ago, when there were about 500 fewer products on the market. Since then launches of targeted ETFs have accelerated, and many of the relatively new products have done quite well in terms of accumulating assets.

There is certainly some merit to the notion that certain corners of the ETF industry have grown a bit too quickly and are positioned for a pullback. Hundreds of funds have failed to attract much interest from investors and are likely losing money for the companies that offer them. At some point, many of the ETFs now on the market will shut down.

But there is room for expansion as well; there are some holes remaining that haven't been filled -- at least not yet. Below, we profile five of the most interesting ETF ideas that have been detailed by various issuers in SEC filings and are at some point in the business development pipeline [for more ETF insights, sign up for the free ETFdb newsletter]:

1. Greece ETF
Greece is a relatively small economy -- approximately the size of Denmark or Venezuela -- but it has captured the attention of investors around the globe for much of the last year. Developments in the streets of Athens have the potential to move markets half a world away, as the European country finds itself smack-dab in the middle of a potentially devastating sovereign debt crisis [see Non Euro Europe ETF Options].

The outlook on Greece's fiscal health has swung wildly in both directions in recent months, and international equity markets have taken their cues from the Euro zone member countless times. A Greece ETF might not attract a lot of long-term, buy-and-hold investors, but it would more than likely become a favorite toy of more active investors who thrive on short-term volatility. If there were a Greece ETF on the market, it seems more than likely that it would have been incredibly active in recent months (and probably made quite a bit of money for one of the issuers out there).

Global X recently detailed plans for a slew of country-specific ETFs, including Greece (Kuwait, Bangladesh, and Morocco were among the others).

2. China Bond ETF
Interest in Chinese stocks has surged in recent years, as the Asian economy has emerged as the primary driver of global GDP growth. There are a number of options for accessing China's equity markets -- 13 ETFs in the China Equities ETFdb Category -- but few choices for those looking to invest in Chinese bonds. The international bond space in general has been slow to develop, in part because of regulatory hurdles related to diversification requirements.

But that hasn't kept issuers from pursuing what would almost certainly be a very popular fixed income product; several issuers have taken at least the preliminary steps towards launching a China bond ETF. Guggenheim made a filing in February for a China Yuan Bond Fund, and WisdomTree recently shed some light on a planned active China Local Debt Fund. PowerShares also detailed a China bond fund recently.

3. Emerging Markets TIPS
There are currently ten ETFs in the Inflation Protected Bonds ETFdb Category, combining for more than $25 billion in aggregate assets. Almost every one of those is invested in U.S. TIPS, an asset class that has become the default option for protecting portfolios against inflation. As investors have grown increasingly anxious about the prospects of a surging CPI, they've flocked in droves to TIPS. That trend, combined with record low interest rates, has pushed yields on these securities close to zero -- and in some cases, negative. Investors seeking to access this shield against inflation have to give up quite a bit in the way of yield [see WidsdomTree Debuts Comprehensive TIPS ETF].

An emerging markets TIPS ETF could give investors seeking this form of inflation protection another option that features a not-so-meager expected yield, as well as dollar diversification and exposure to an alternative gauge of inflation. So WisdomTree's recent filing for its Emerging Markets Inflation Protection Bond Fund could be one of the next innovations in the fixed income space. The proposed fund would invest in inflation-linked debt of issuers in Asia, Latin America, Eastern Europe, Africa, and the Middle East. According to the filing, the portfolio would include debt from countries including Brazil, Chile, Colombia, Israel, Mexico, Peru, Poland, South Africa, South Korea, Thailand and Turkey.

4. PIMCO Total Return ETF
The excitement surrounding this PIMCO's Total Return ETF began to build in April when the company filed for approval on an ETF version of its ultra popular Total Return Fund, the world's largest bond mutual fund. The proposed active ETF, which would charge 0.55% in annual expenses, would be managed by bond guru Bill Gross, the Warren Buffett of the fixed income world.

Given the impressive track record of Gross and PIMCO as a firm, this fund -- which will be traded under the ticker TRXT -- could quickly become the largest actively-manged ETFs. TRXT will blow through AUM milestones more quickly than any ETF to debut so far in 2011, and could challenge existing products such as AGG and BND.

5. India Sectors
India is one of the world's most exciting and terrifying investment destinations; the BRIC member maintains a long term growth forecast that not even China can match. By some estimates, India will be the world's largest economy by 2050. ETF options for accessing India have become increasingly granular in recent years -- we've seen the introduction of a couple of small-cap funds (SCIN, SCIF) and an infrastructure product (INXX) -- but the tools available for those looking to access this economy remain somewhat limited. Fine tuning India exposure through ETFs is tough, and any sort of sector rotation strategy is out of the question. Considering that there are five biotech ETFs and multiple copper miners funds, the lack of precision surrounding India seems like room for growth in the ETF space.

Both EGShares and Direxion have filed for regulatory approval on India sector funds. Included in both filings were India consumer ETFs that would be the odds-on favorites to be the most popular among the respective suites, considering the tremendous interest in products such as ECON (about $225 million in AUM), CHIQ ($205 million), and BRAQ ($28 million).

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Disclosure: No positions at time of writing.

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