Like the most popular girl in school, Vanguard gets valentines from everybody. Here's another reason to bring Vanguard some flowers.

In the financial services industry, where unscrupulous money managers often prey upon unsuspecting clients, Vanguard is a breath of fresh air. Few companies are so focused on delivering a quality product for their customers.

Investors cannot control their portfolio's return, but they can control its diversification, and the costs it incurs. Vanguard has been a leader in low-cost index funds, but it's not the type to rest on its laurels. The company has filed registration papers with the SEC to offer exchange-traded funds (ETFs) for four of its index bond funds: Vanguard Total Bond Fund (VBTSX), Vanguard Short-Term Bond Fund(VBISX), Vanguard Intermediate-Term Bond Fund (VFIDX), and Vanguard Long-Term Bond Fund (VBLTX).

Currently, only Barclay'siShares ETFs offers bond index ETFs. Vanguard's foray into this arena definitely bodes well for investors, since its bond ETFs will have lower annual costs than iShares. Costs are more important with bond ETFs, since bond funds' returns are significantly lower than their stock counterparts. Some in the industry speculate that Vanguard will struggle for market share against the well-entrenched iShares, pointing to the failure of similar offerings from ETF Advisors LP. But that firm was undercapitalized -- hardly a problem at Vanguard.

Vanguard's proposed ETFs contain a greater number of securities than existing offerings from Barclay's. Total Market Bond Index Fund holds 2,801 securities, compared with the mere 125 in the iShares Aggregate Bond ETF. More securities will protect the fund from potential defaults, while helping the Vanguard ETF more closely track the Lehman Brothers Aggregate Bond Index to which it's linked.

Other industry players are rolling out a dizzying array of costly ETFs, such as the upcoming PowerShares DWA Technical Leaders Portfolio. This (supposed) index sports the industry's highest annual cost, a whopping 0.60% expense ration. Conversely, Vanguard focuses its efforts on an underserved area of the ETF landscape, and does what ETFs do best: delivering needed diversification at a low cost. In my opinion, that's worth at least a dozen roses, if not a box of chocolates, too.

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Fool contributor Buz Livingston, CFP, appreciates your feedback. He owns none of the ETFs listed but uses iShares and Vanguard ETFs. The Fool has a disclosure policy.